Have never sold a gun on GB, only buy. I only started buying a couple of years ago, and don't buy often, but I have made a few observations. I never look at auctions with only a reserve. I don't want to waste my time chasing an unknown reserve amount. I do, however, sometimes look at auctions with both a reserve and BIN. Most times, the BIN price is about twice what the gun is worth, but occasionally the BIN price is reasonable. I always do my research and questions before ever submitting a bid. I know what I want, what condition I want and the current fair market value of what I want. Regarding questions, if a seller will not answer my email (in spite of what they may say on the auction description) OR does not reply with a direct answer to each question, I walk away from the auction. I assume they know something they don't want potential buyers to know. That just aggravates the crap out of me. Just in the past few days, I asked a seller of a used revolver if the lockup and timing were correct. I asked if the rifling was sharp and crisp. I asked if there was any rust or pitting in the charge holes or barrel. I asked if he would accept a C&R (gun was manufactured prior to WWII). His email response was "gun works fine". So what does this say about that particular seller? He has an A+ rating and has sold over 3,000 items on GB. Why would he not answer my questions? If a firearm obviously qualifies as a C&R, and the seller will not accept my C&R, I walk away. I refuse to do business with someone who refuses a legal transaction. I have found that individuals selling a gun are much more responsive and forthcoming with additional details when asked than most FFL businesses are.
I don't care how nice a gun looks, how bad I want it or how cheap the price is when the seller has no idea what he/she is talking about. I was looking at a very nice stainless revolver a while back, the seller described it as having a "chrome" finish. While that is not an impossibility, this gun absolutely did not have a chrome finish. On the flip side, I have seen sellers describing nickel guns as stainless steel. I expect sellers to be at least reasonably informed of the product they are selling. If not, I just skip right on by.
Buying from gun auction sights can be enjoyable and reasonable price wise. Using a bit of caution and common sense are key.