iTrader question

Hi.
I recently did an auction for a domain, and someone made the highest bid but now refuses to pay.

Am I allowed to leave a negative iTrader?

To me, it seems quite apparent he only bid to get his post count up.. I mean, how can you lose interest in a few hours?

 

If they placed a bid and didn't retract it during the active auction or something, then they committed to deal terms, so yes - you can leave them negative iTrader as they initiated participation in a deal by bidding and committing to those terms.