Is Clean Master a legitimate app? My phone ASUS Zenfone 2 came preinstalled with Clean Master by Cheetah Mobile. It claims to do a lot of things like deleting junk files, freeing up RAM, controlling device temperature, increasing battery usage etc. My question is does it do any of those things? Frankly I don't see much difference after it says it has freed up RAM. Also it has a bunch of ads which tries to get me to download other apps from Cheetah Mobile