I appreciate the concerns over favoratism in player ratings. I think its valid that you can only give someone a rating if you actually played with him/her. Also, I think I would make it so that you get 1 positive per game played, regardless of the number of positives given to you for that game. A positive and a negative would co-exist on the same game, and regardless of the number of negatives it would be a max of one point per game either way. If more than one person had issue with the player in question, the comment entries would indicate it. Hecx you could make the positive a default, and it only gets countered with a negative (guess that would be the same as a negative-only system).
Dispute resolution is up to the two or more individuals at odds with one another.
The rating system isn't so much about accumulating positives, but, then again, why should not someone who attends a lot of games accumulate a lot of positive ratings if he/she deserves them? What is wrong with that? And it also indicates that the person is consistently reliable and plays without a hassle - this is good to know for all of us.
Either way, it would provide a very public place where misbehaviour is identified and quite immediately. My thinking is that it would help cause corrective action to occur much earlier in an airsofter's playing career as opposed to accumulating a ton of crappy games and by that time the person is beyond redemption in the eyes of a lot of people in the community.
Why shouldn't negative behaviours be addressed in such a system? People can already engage in online character assasination, and it happens now and again, but not regularly because ultimately you still need to co-exist to play. Those same impulses and motivations are there regardless of this system. Its just with this system its a little more clear and immediate.