There is a lot of talk on this subject.
Would it be impossible to have 2 types of feedback? One for normal sales and purchases good or bad (restricted access in some way). The other devoted to npb. Thus avoiding good feedback being eaten up by revengefull npb.
I assume that the problem stems mainly with buyers therefore the feedback system could rely on seller placing feedback before buyer was allowed in. Therefore if seller not happy they do not leave normal feedback, so npb can not either, but seller leaves a bad mark against the npb feedback.
Problem solved - well on the way anyway!! :roll: