There are 2 sides to every story... a bad deal or something that upset someone, may have been completely different than they make it out to be. No point giving someone a bad rap because 1 moron didn't like they way things went, and no point giving someone a good rep just because your there friends and you want to bump there rating up so they can rip someone off.
Word of mouth spreads quickly here, if you are a good seller, people will make that known.