A problem on forums was people quoting large comments, adding their response of "this" and then an additional signature. Digg and later Reddit moving that junk out of sight and gradually educating people not to do so was a big win.
Glad I'm not the only one to immediately think of it. It's a great story, but did feel unlikely when I first read it; should it prove largely true it would be terrifying.
The sponsored spot is appalling, I reported something that looked dodgy which appeared above the UK gov identity verification for passports and such app. When people search for a specific app, putting something else in front only makes me think you are untrustworthy scum, so my trust in the play store is fundamentally broken. There's a fundamental incompatibility between giving the right result for what was searched for and pushing promoted irrelevant results.