I had the same thing about 2 weeks ago. I was trying to sell a KTM 250, this guy had got on and drove bids up to about $6k, then 24 hrs later had retracted his bids saying he had entered the wrong amount (How the F%^K do you do that 3 bids in a row). After checking his bidding history, he had done the same thing to 13 of the last 15 bids he had placed in 3 months.
I then offered it to the other bidder but they only wanted to pay the highest bid at the time ($3.5k) before this other dickwad got on. Even though there highest overall bid was $6k.