Well, I think the most worst app would be apps that take you to some thing different than you accept for, recently i have downloaded an app from the mobile9 apps screen shot looks like its a gaming app but when i installed it takes me to completely
different place some arabic words are appearing with ...... pictures.
hehe ...LOL but agree with you John. such apps are spams.They may be even designed to steal your personal information like email id , phone model , phone number etc. Even antivirus will not be able to detect them as it could be functional requirement. So guys , when you install app , please do check , if such apps wants account/contact read permissions.
but since many advertising Platform needs the info , and apps including advertisement will ask you for account/contact read permission. I don't know how to deal with them.