Auctions
Shills, or potted plants, are sometimes employed in auctions. Driving prices up with phony bids, they seek to provoke a bidding war among other participants. Often they are told by the seller precisely how high to bid, as the seller actually pays the price (to himself, of course) if the item does not sell, losing only the auction fees. Shilling has a substantially higher rate of occurrence in online auctions, where any user with multiple accounts can bid on their own items. Many online auction sites employ sophisticated (and usually secret) methods to detect collusion. The online auction site eBay forbids shilling; its rules do not allow friends or employees of a person selling an item to bid on the item.
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