True, there's plenty of things to worry about in the Play store. Plenty of malware to go around. The problem is, antivirus apps do almost nothing to protect you from Play store malware.
Here's a list of
just a few the vendors and apps which have serious enough problems that they should be considered malware.
Not one of the apps listed will be detected as Bad News by any antivirus app. Some are truly horrible. Any software from these companies should be considered to be malware. They may have serious privacy concerns such data-mining and sending your data to servers in China or elsewhere for who knows who to do who knows what with it. They may throw up nag ads or scary-sounding bogus warnings urging you to buy more software or else Bad Things will happen in order to get you to buy and install more of their malware. They may simply be ineffective or worse. Or they may be all of these things. But for some good reasons they are all crapware to be avoided like the plague or they would not have made this list.
Bad Vendors:
Cheetah Mobile (All the CM stuff, QuickPic and more)
DU Apps (DU Battery Saver, DU Speed Booster, others)
Baidu (Baidu Browser, Photo Wonder, others. Baidu owns DU Apps.)
Go Development Team (All GO apps)
360 Mobile Security
Apus Group
Bad Apps:
All CM apps including:
Clean Master
CM Security
CM Speed Booster
CM Keyboard
CM Flashlight
CM Backup
Battery Doctor
QuickPic (recently bought by CM/Baidu)
Photo Grid
Snap Share
File Manager
File Manager HD
File Manager Pro (there are legitimate apps also called File Manager)
...and more
All Baidu/DU Apps including:
Baidu Browser
Photo Wonder
DU Launcher
DU Battery Saver
DU speed Booster
DU Privacy Vault
...and many more
All Apus Group apps including:
Apus Launcher
Apus Browser
Apus Booster+
Apus Message Center
...and more.
Misc bad apps:
Cleaner Master (not the same as Clean Master)
360 Mobile Seurity
KK Browser
Boat Browser
UC Browser
Dolphin Browser
Maxthon Browser
...and many, many more.
ES File Explorer: See: this about ES File Explorer security concerns:
http://androidforums.com/threads/es-file-explorer-privacy-security-concerns.914178/#post-6941798
...and
http://androidforums.com/threads/problem-with-es-file-explorer.907922/page-2#post-690973
Also, not malware, but email apps with privacy concerns: (and some without).
See:
http://androidforums.com/index.php?posts/7051405
Sooo...what is antivirus protecting us from? I've used Android since v1.0 and never seen antivirus stop a single legitimate threat. But it IS good at using a lack of knowledge, fear and paranoia to turn your money into theirs.