As it is, the mentor crown seems to be attracting the wrong kind of people. I've seen more horribad and outright rude mentors than helpful/skilled/nice ones. There have been reports of mentors trying to votekick sprouts for not running dungeons fast enough. All because of the rewards.

IMHO there shouldn't have been any rewards for mentors to begin with. That would have meant far less mentors, of course, but those with the crown would have probably been at least somewhat better than the ones we have now. The crown itself is a kind of bling bling item too, a watering can might have been better.

I'm not sure if there's anything that can be done to "fix" the current situation. Maybe take away the crown (+rewards?) from the player if he/she gets reported often enough? Maybe have a separate commendation system for mentors with both up and down votes? That would probably be abused, though.