I don't think its so much a question of belonging to a clique as it is having a basis for people to judge your ethics.
There may be several posts following this in respect to how misleading feedback can be. How people avoid giving negative feedback to avoid getting negative feedback etc.
While all these things carry some weight I think a person is more apt to want to do business with someone who has a good record as opposed to a poor one.
Unless the seller/buyer is personally known to you what else do you have to go on?