What Lume said is right when it comes to toribash and some other bidding.
In toribash, if the winning bid didn't send what was due, he must pay the auctioneer 40% of what is due to him.
In real life, it is not always the highest bidder who wins the auction. It depends on the auctioneer on who he wants to pick. Because for example when buying materials, others bid with low prices but also with low quality.