It's called the bidding scam:
1. You want to sell an item, say XPY
2. Honest guy bids $0.20 hoping to make a good deal.
3. Market knows that fair price is say $3.
4. I want to take it off you so i see highest bidder is $0.20 so I bid $0.25.
5. I login from another account and bid $4.5
6. No one will bid any higher anymore because people don't think that it is worth so much.
7. At the last minute, the $4.5 offer cancels the bid and in the case of tonight, withdraws the buy offer
8. I win your item for $0.05 higher than the highest bid the time I came to get you at.