First, in forums where the trust list is visible it might be handy to have a "Trust User" and "Exclude User" button added.
This would be a nice thing to have. Adding someone to my trust list is a bit of a hassle. Not much, but having two buttons, makes it a lot easier.
Somewhat related to both systems, is it worth investigating an additional level(s) of feedback in the system? Currently there's not really a difference between "This person is acting in a sketchy/slimy way, I don't trust them" and "This person stole 100BTC from me" in the numerical ratings. If people used it properly a separate rating for personality conflicts / general sleaziness as opposed to a full negative scammer rating might see the system used more. I can think of many people I wouldn't personally buy from / do business with / trust, but I don't want to leave negative feedback for given the gravity of it. I have my doubts such a thing would be used properly and personality issues still wouldn't just garner the same 9999BTC risked "This guy is a scammer!1!! He was mean to me in my for sale thread!!1!" feedback we see now.
I think this is very idea. #bitcoin-otc has -10 to 10 as rating possibility and it helps a lot.
You know someone in person, you two are friends and you would trust him/her with your life? +10. You did a small trade? +1. You don't trust this user because of personality? -1. See
Rating guidelines for more. I often feel that a negative is too harsh, so I go back to neutral, even though that doesn't fully reflect my opinion about someone.