I fell for the MacKeeper deal a few years ago. But used AppCleaner to get rid of it. It seems to have cleaned out all related files. Now I only use AppCleaner to remove any app from my machine.
How does that work with SSL certificates? Because that's one of the two main reasons for using SSL in the first place: Being reasonably sure that you entered the correct address, and keeping your interactions with a site reasonably hard to read for third-parties.