Doug Ochoa and his brother Tom run their postcard company in Florida. They also own the closing company they use. Others may have a different experience, but I bought two of my four timeshares from them off eBay, and I had no trouble whatsoever. I half-expected a horror story, based on what I was reading here, but I can truthfully say they delivered on everything they said they were going to do. I would buy from them again, if they had what I wanted to buy.
When one closing seemed like it would take longer than I wanted, and I felt I might lose valid use of the week I was getting as part of the purchase, Doug made a reservation in advance at my request, so when the deal closed I already had the reservation I wanted. He was very helpful to me.
My advice is to do your due diligence very carefully ahead of time, and make perfectly clear you're bidding on what you think you are. If you don't trust what you're reading, don't bid.
Good luck!
Dave