At an auction, the auctioneer looks across a sea of faces, and all the faces look back at him. Since bidders have a variety of secret signals, it's common for other bidders not to know where competing bids are coming from. These are phantom bids. The result, however, is the same. The real bidder is tricked into making a higher bid.
Some auctioneers try to avoid the blemish of calling phantom bids by renaming the practice.
If a rose by any other name is still a rose, then so is a cesspool, and that's where phantom bids belong. It can be hard to impossible, especially for auction novices. The speed, excitement, and activity that surrounds auctions is a perfect camouflage, but there's an effective counterstrategy. Search out auctioneers who have a reputation for integrity. When you identify an honest auctioneer, patronize him and let him know how much you appreciate the way he does business.