But is there even such a mod like that? Besides, people would probably mess with other people's "trust" if they were allowed to score someone on "trust".

What I'm saying is this, if Admin were to install a type of "rating" thing. Where you could rate a user from 1-5 stars, some would go and intentionally do something to another user like rate him a 1 just because they don't like him, and he would be docked points in the "trust system"