Is MacKeeper a contoversial App that new Apple Users should be educated to stay away from? I see adverts for this particular app all over the place. Is it true that people should stay well away from it, as it could potentially do more harm than good to your Apple Computer, and to your wallet!!
It's certainly true that the app is controversial - search the Apple Discussions site for more on that - and while there were certainly issues with early versions current versions are reported better. 

However, there are many with very significant reservations about the sales tactics the company uses - pop-ups, paid-for recommendations on review sites etc - and that its uninstaller didn't work for many versions, so users kept getting further advertisements, allied with the  facts that the things the app claims to do are either a: unnecessary or b: can be done with free or cheaper alternatives means that the app undeniably has a bad name with many Mac users.

And again, for citation: search the Apple Discussions site for much, much more about this app.