I wouldn't let it turn me away if it was a lone negative among many positives. I know that I personally had a bad experience as a seller here on Audiogon with a real psycho. Even though he was unreasonable and dishonest in our transaction, I just wanted to protect myself and my positive feedback, so I let him have his way. My point is that sometimes, a good seller will get a bum rap from a bad buyer, and vice versa.