When it comes to battling AutoTrader.com scams, well, most online scams, I would just like to add that the best way I know to guard against being ripped off by online sales or auctions, Penny, Craigslist and eBay included—and whether seller or buyer—is to use a bona fide online escrow company. This is especially true for pricier items like antiques, jewelry and autos. Yes, it does add some cost, but it takes the uncertainty out of the transaction, and that is usually a small price to pay for peace of mind.
For my money, the best bona fide online escrow (and there seems to be ten or twenty fraudulent escrow sites for every bona fide one) is Escrow.com (http://escrow.com). In fact, that is the only site that eBay recommends, and is the only online escrow company that is licensed to provide escrow services all across the United States.
PS. You can find more information about battling online scams and frauds at Online Escrow at Wordpress.com (http://onlineescrow.wordpress.com/)