People are people.
I prefer to befriend the ones I like. I ignore the others.
Although I've never sold a bike through Bike Forums, I did sell a bike to Bike Forums member. I had bought a highly desireable bike at a great price. I was uncertain of the value, so I posted pictures of it in the "What's It Worth Section". In my thread, I listed the price that I had bought the bike. Later I listed the on ebay for the value of the bike. The bike only had one bid, but I made sustantial profit over my purchase price. Because the Bike Forum member knew the price that I had bought the bike, he kept trying to renegotiate the price. He asked several times to lower the value of the winning bid. After seeing that I would not budge, he asked for free shipping. I've never had someone try to renegotiate the price after bidding on an agreed upon price. Since then, I rarely list the price in which I purchase a bike.