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Clean Master: "You have a right to complain"

Clean Master (Boost & AppLock) is an app which claims to be able to increase device performance by a substantial amount (80 percent, according to its Google Play page). Despite its popularity – Clean Master is reportedly present on more than 600 million phones – many people in the Android community question its functionality and have concerns with the way it promotes its features.

I interviewed Clean Master last month and a few days ago had the opportunity to follow up with Jill Shih, the Vice President of Product and User Experience at Cheetah Mobile, and Brett Ting, Clean Master’s Developer Manager, with some further questions.

AndroidPIT clean up master 2 app screenshot 1
A look at the Clean Master interface. / © AndroidPIT

Boost feature

I asked if Shih and Ting could demonstrate Clean Master's performance boosting functionality for me. 

“It could be tough right now. To really be fair, we need to have two identical phones,” said Shih.

“Would I not notice [Clean Master working] without another phone that’s identical?” I asked.

“From an experiment perspective, if I run a scenario, a first time and then a second time on the same phone, there could be other factors. I’m just thinking out loud here. There could be other factors that are impacting the result, that we probably don’t know of.” Replied Shih.

I asked if they thought it was a problem that a user who downloads and installs the app may not see Clean Master work.

AndroidPIT clean up master 2 app screenshot 5
A system vulnerability message displayed when opening the app (left). / © AndroidPIT

Shih and Ting conversed in Mandarin. “We can try that later on. Can we do it later? I want to maybe borrow a Samsung.”

I asked why.

“Samsung has too many pre-installed apps,” said Ting. “Not like a Nexus.”

"I want to maybe borrow a Samsung.”

Shih added that Samsung phones are very popular, but I asked again why she wanted a Samsung specifically.

“To feel the results more obviously. Does that make sense?” Shih said. “[Samsung users] are the majority of Clean Master’s users.”

AndroidPIT clean up master 2 app screenshot 6
"Your privacy is leaking," warns Clean Master on the lock screen (left). / © AndroidPIT

“So the Sony phone I have here or the Nexus you have, these phones would not work?” I asked. 

“It will work. For users to feel, I guess, also depends on how many apps you install and what kind of apps you install [...] we are just saying that Samsung came out with more pre-installed apps. At least our Samsung users, out of the box, they will [be more likely to] run into this problem, like lagging, slowing down, running out of storage.”

The Clean Master team, for the second time, failed to demonstrate that their app works as advertised. I told Shih that she could email me after the interview with some supporting evidence, if she wished. I will update the article if it arrives. 

CPU Cooler

I also asked Shih and Ting about the 179 degrees Celsius warning I saw on the device after the last interview (see below). They said that it must be a bug, but Shih admitted that there are occasions where a device heats up to the point where she “can not even hold the phone.”

I was skeptical of these claims. “It doesn’t matter if [phones] get warm because they're meant to get warm. You can’t charge a device without it heating up.” I said.

“I need to disagree with that. Mechanically, the CPUs get warm, mechanically a car gets warm when we drive it. But it doesn’t mean that users [could] not want to cool it down.”

Shih explained the reason behind Clean Master implementing the feature.

androidpit clean master app 57
The screenshot on the left suggests the CPU temperature is considerably high. Clean Master says it's a bug. / © ANDROIDPIT

“Most of our users are not tech savvy, they just want to use the phone. They actually don’t want to worry about RAM, ROMs, storage, temperature [...] they want Facebook, they want Google, they want to call, they want to email.”

Shih continued: “We know the system; you know the system; you know it works. However, our users don’t. And we can do things to help users, to make their Android lives easier."

“[Heat] is something that users can feel [...] so that’s actually why we work on this feature, this functionality. It doesn't mean that we just want to cool down the temperature, it means temperature is something every user can understand.”

“Most of our users are not tech savvy."

Shih said that Clean Master doesn't want to “throw a lot of technical words" at its users, and added that, “Some of our users are like grandmas and grandpas, they don’t want to worry about that.”

I asked if Clean Master is best suited to Android users who don’t know much about phones.

“No,” Shih said. “At the end of the day, we want Clean Master to be on every single Android device in the world [...] I’m not saying [our] users are not smart.”  

AndroidPIT clean up master 2 app screenshot 2
Clean Master's in-app antivirus page warns of "account and monetary loss" (right). / © AndroidPIT

I told them I’d never worried about overheating in my smartphones, despite the fact that they do get warm.

“There are a lot of users in the world who don’t understand how Android works [...] when the phone gets warm, they might worry.“

“Yes, there are a lot of people who don’t understand how it works and that’s how Clean Master can be a success,” I offered.

“I disagree with that,” Shih replied.


Functionality aside, another concern the Android community has regarding Clean Master is its advertising. A couple of Reddit users provided me with some online warning messages which suggest that viruses are on a person's phone and that they must download a security app to remove them. I used one of the messages in the interview to underscore my concerns with fearmongering with regards to security app downloads. (For clarity, Clean Master is not responsible for the two screenshots directly below).

androidpit malware images 1
Two examples of marketing techniques employed by app developers. / © Imgur / AndroidPIT

"It’s beyond misleading”. Shih told me, of the left screenshot above, which prompts users to install 'boosting' app DU Cleaner.

I followed up by showing Shih and Ting a message from the Clean Master app. “It says ‘intruder alert, someone tried to snoop on your phone’ exclamation mark. Why is this different?”

“These aren’t the same,” Shih said, of Clean Master and DU Cleaner's message. “But since you don’t feel comfortable [...] I think maybe, I'm sure, there is room for improvement on our side. But we’re not trying to scam users.”

I asked again why the app is telling me something that is untrue. David Wu, Chairman of Cheetah Mobile’s marketing partner Leopard Mobile, who I interviewed previously, had entered the room and was looking at the messages.

“It’s beyond misleading.”

“You have a right to complain,” he said. “But it’s still a different level. [The DU Cleaner message] is false advertising, that is completely prohibited by Google, that is something that we will never do. We actually capture [that] stuff and report it to Google.”

AndroidPIT clean up master 2 app screenshot 3
The intruder alert message I presented the CM team with (left). / © AndroidPIT

I referred them to the intruder message once again.

“I do see that the wordings are too strong and they make you uncomfortable, they make you feel threatened [...] I’ll talk to the team. I’ll review all the wordings.” Shih said.

After changing the app language to "Chinese", Shih told me that the wording used there was softer than in English. In Chinese, it doesn’t say someone has been snooping on your phone. Shih said it says: “privacy risk, your phone can be snooped [upon].”

“It’s still an oversight,” said Wu, regarding the English translation. 

AndroidPIT clean up master 2 app screenshot 4
The intruder alert message directs users to CM Security, another Cheetah Mobile product. / © AndroidPIT

Final thoughts

Before I left the interview, Wu confirmed that within the next 30 days they would “review the language in the English app.” While it's encouraging to hear the Clean Master team say it will take steps to investigate the language of the app (whether this will happen remains to be seen), it's still concerning that they have been unable to show me the app working as it's intended. 

This is the second time that I've spoken to Clean Master representatives in person about the product: how hard can it be? If I had a phone with my app installed and somebody asked me to show them how it works, I would just show them.

What are your current thoughts on Clean Master? Let me know in the comments.

Thanks to the folks who commented on the previous article and in /r/android/ for the advice and suggestions.

Readers' favorite comments

  • Mark 2 months ago

    Your last article stated it is the 5Th most installed App. After all the comments I still think it must be the number one in uninstalled Apps.

  • Brett Handley 2 months ago

    I've had Cleanmaster installed on both my phone, a Samsung, and my tablet, a Lenovo, and have found both work better once the app was uninstalled.


Write new comment:
  • Angelo 2 months ago Link to comment

    I fix phones for a living. Most of my clients are not technically savvy. I can tell you that 99% of the phones that I look at have one or more of these fake apps on them. The users have NO IDEA how or why the app is on their phone (most were likely duped by the false bait). And the biggest complaint most of these people come to me with is that their phones are slow or their battery doesn't last. I ALWAYS uninstall these nonsense apps because they are among the biggest culprits that are clogging up these phones and wasting battery power!

  • Total load of crap! dosent do anything that you can't do yourself only when you do yourself it uses a lot less battery.

  • Alec B. 2 months ago Link to comment

    Yes, I was sucked in on 'virus fear & rubbish' ... and I loaded 'savers' that said they "did this, did that" ...and cleared cache's ,,I used it then, checked an app, it wasn't cleared at all ! .. my mobile had been dropping or losing individual icons or replacing them with an Android figure, this meant I had to reinstall, double up same icon then remove 'fakes' ...this got really stupid ! ..13 icons mucked up !! sometimes daily I uninstalled 4 old apps, then removed all Cleaners and 'fake protection'
    That was last week ... not one stuffed icon, no choking ad rubbish .....and my battery life has improved tremendously !! ... and I use my Samsung ZOPO 9999 Smart mobile constantly !!
    As per everything else ....lies and fear abound make Developers big bucks !

  • Mark G. 2 months ago Link to comment

    I've never used any of these performance improving apps. As they said quite clearly this type of app is for those who are ignorant or uneducated in how Android works.
    I rarely clear my recent apps list and will occasionally switch my phone off/on but have come to realise that even doing this probably wastes more as everything has to restart.

    To say that Samsung devices need this type of app due to having more pre-installed apps is utter rubbish. My excellent Samsung Galaxy S5 is still as sharp as day 1.
    There is absolutely no situation that Android devices would be presented with that would be helped by having these types of apps.

    I can understand why certain people who are anxious about viruses and ID theft and who are unconcerned about learning how to actually use a Android device will use these apps. The Developer's are fully aware that these are the type of people to target. It's a way to make money out of peoples insecurities.

    This makes every aspect of these types apps dodgy to say the least...

    Sign up for the excellent Androidpit newsletter and you will soon become Android intelligent.

    Peace ✌

  • How can Cheetah Mobile claim to offer a performance boost but not be able to demonstrate it. You would think they would have performed some in house testing before making such a claim.

  • Albert 2 months ago Link to comment

    I actually do worry about my phone getting hot. I live in Arizona and when you are working outside in 105+ weather my s7e gets hot quick! But I do believe these apps don't work at all. I had CM and right now I have DU. When I check if I need to clean my phone it always tells me i have 4GB of junk and I don't believe it because if I check it in an hour it tells me i have 4GB of junk again.

    • Yes yes, you're right, of course you should keep your device out of sunlight or try to keep it in cool conditions -- as with most electronics devices. I'll write a short update to explain what I mean. Essentially, I just meant that managing RAM or reducing the CPU load isn't necessary in order to keep a device cool.

  • Take 'em to the cleaners

  • skyrail 2 months ago Link to comment

    After spending a few days thinking about battery saver, optimizers and so on, battery drain and device getting hot too fast, I must admit I agree Antonie S.
    I removed CM, Greenify too and disabled smart manager doze.
    Just installed DU Battery saver last version.
    Also decided to not kill app in memory too often, and keep it running. Regularly kill background app and notification to save battery.

    This new strategy seems to work and let me have a fast device, keeping temperature under 40°C.
    Before that, I had to run CM and wait for deleting cache and junk files. CPU cooler seems more efficient in Du battery saver.
    But the worse was CM responsible for hot battery, strange cpu behaviour, after a few weeks.

  • andy 2 months ago Link to comment

    I've just spent two minutes writing only for you to say that there was unapproved content ,so battery app and cleaning app don't do anything at all except use battery life and I don't like anything made by cheetah as there will of ads

  • Agreed

  • CCleaner is far better , working great and simple.

  • I installed CM on my two identical note 5's, it worked differently on each phone, . My concern is I feel their app is misleading and false advertising. It does little to nothing to help your phone and in fact it actually slows down the phone quite significantly and drains the battery horribly. I was in fact part of the beta team for almost 2 years, that is until I learned better and Uninstalled the app. They should be made to be more transparent and forth coming about the app or be made to take the app down.

  • Mark 2 months ago Link to comment

    Your last article stated it is the 5Th most installed App. After all the comments I still think it must be the number one in uninstalled Apps.

  • Alex R. 2 months ago Link to comment

    I have been reading articles all over online and in here too some articles tell not to install ram manager cache cleaner apps and others are sponsered and asks people to Download them what the heck are you thinking and doing in here ?

  • I've had Cleanmaster installed on both my phone, a Samsung, and my tablet, a Lenovo, and have found both work better once the app was uninstalled.

  • especialy cleaning cache makes no sense because it makes your phone slower

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