Is This A Shill?

One simple technique: ShillA bids a ridiculously high bid. That advances the auction to one increment past your highest. That ridiculously high bid is withdrawn. ShillB, now knowing your high bid, bids one increment or less below your high bid. You "win" at your high bid. ShillA and ShillB could be the same person. If the current bids are in the $200s, if the ridiculously high bid has an extra zero at the end, eBay is likley to believe that $2400 was a MISTAKE, and was intended to be $240. The other common technique: ShillA simply bids competitive bids. If ShillA accidentally wins, then the bid is withdrawn, as a "mistake", and the seller offers you the item "second chance" for your now-revealed high bid, instead of the highest that it had gotten to before ShillA's "mistake".