Most people who complain to the FTC about Internet auction fraud report problems with sellers who:

* fail to send the merchandise.

* send something of lesser value than advertised.

* fail to deliver in a timely manner.

* fail to disclose all relevant information about a product or terms of the sale.

Some buyers experience other problems, including:

* "bid siphoning," when con artists lure bidders off legitimate auction sites by offering to sell the "same" item at a lower price. They intend to trick consumers into sending money without delivering the item. By going off-site, buyers lose any protections the original site may provide, such as insurance, feedback forms, or guarantees.

* "second chance offers," when con artists offer losing bidders of a closed auction a second chance to purchase the item that they lost in the auction. Second-chance buyers lose any protections the original site may provide once they go off-site.

* "shill bidding," when fraudulent sellers or their partners, known as "shills," bid on sellers' items to drive up the price.

* "bid shielding," when fraudulent buyers submit very high bids to discourage other bidders from competing for the same item, then retract their bids so that people they know can get the item at a lower price.