Shilling happens at regular auctions too, and it can backfire there as well. When the seller sees his item sold at an auction he expects to get paid for it, and if the auctioneer was the last bidder, he owns it. ince an auction is a standard way of conducting business, with fixed notions on the part of the buyer as to how it will be conducted, and since most sellers don't advertise that they are going to shill the auction, bidding up your own prices is of course fraud, and doing it across state lines, where the internet goes, makes it something you can go to jail for, tho, that doesn't seem to bother some folks....
I have never understood ebays excuse that private listings are to protect the seller identity, most sellers on ebay are using fictictous names to start with, who cares if joe12345 is the high bidder???