If the students are being honest in their exit tests, then mentors that don't do anything won't gain mentor points.
I'm not saying we get rid of Mentors, just get rid of requiring it to be a subclass. Put an option in the Actions page that lets you declare yourself a Mentor. I do think, though, that this requires some way for the game to evaluate the performance of Mentors. Get too many bad reviews, and get booted from the Mentor program for X months.
