You have an auction at flippa, it does not succeed, then later an original bidder approaches you after the auction and wants to buy. So, you sell it to him.
Did you know that flippa searches the "Who Is" site to see if failed auctions have been sold later on ? They sent me an email telling me they did this. If they see the ownership change after an auction, they will send you an email saying congratulations on the sale of your domain - now you owe us $200.00.
Kind of interesting - I looked in the terms and conditions and it only says if you sell to another buyer during an auction (not after it), then you owe them.
Not sure this practice is very good at all, but anyway I guess they need to check up on sites down the road after an auction failure. Actually they made enough off me by charging me for promotion of the auction that did not succeed, but what can you do ?
So, if you sell sites on flippa, be careful.