I've heard that there is a malware purveyor who masquerades as Mac Keeper. I've also heard that Mac Keeper itself isn't a very highly rated product which has had allegations of deceptive practices lodged against it, including possibly even being malware itself. In any case, it certainly seems like something to be avoided.
Quite frankly, if I found myself sitting in front of a computer with that on it, I'd be inclined to do a full clean internet install of macOS on the spot.