With some of the knuckedraggers that post on there I would think they would rather just close them down.
Comradehunt: There is a trader on TM who gives people negative feedbacks (by default) if he is not given (a happy) feedback. Thats it - trade can be 100% a pleasure and success, but if he doesn't get feedback - you get a red!
To expand on this, say after a few weeks no feedback has been given to him, he writes an email blackmailing that either you give him good feedback right away, or he will post negative, which will stay there until a happy is given (even though affected person still has a red, crazy).
NonprayingMantis: IIRC, feedback can only be amended once be each party.
So, if he does that, and gives you a negative, but then subsequently changes it to positive or neutral when you give him a positive, then all you do is change his to negative for being such a douche.
since he has already edited once, he cannot do it again.