Aion actually sorta had a thing where you could pull up people's character profiles to look up their gear + stat, etc. but, you could also leave COMMENTS on their profile. This being a PvP oriented game, and myself playing an assassin those comments were usually made by upset players. Not that I minded. Some were rather funny. Something along the lines of "You gonna need a rocket or a ladder that's foreva to get on my level" - quality comments like that. Eventually it became such an issue that they removed the comment feature entirely. I admit I was a little disappointed because I took every rage comment as a badge of honor, but a lot of people didn't quite see it that way I guess.

Lineage 2 had a thumbs up system. If you got enough thumbs up your name would change blue which would indicate people liked you. It was a neat idea except you'd just bug your friends to thumbs up you. Or in some cases some people would pay strangers to thumbs up them.

I dunno OP, even yelp has people exploiting it. I doubt any real useful rating system could come from a video game, especially since you're dealing with people who can change and learn on the fly, opposed to companies stuck in bad business practices.