I do a ton of business on Ebay all the time, primarily as a seller but also as a buyer.
There's some things i've learned directly and indirectly from my experiences there. This list is by no means complete, but covers most of my experiences. To date i've been lucky to not lose a single dime as a buyer or a seller.
1. "Private Auctions" for anything but pornographic material means the seller has something to hide. More than likely, he wants to keep people from warning the bidders on his auction that he is a fraud.
2. Using Western Union, Cashiers Check or Money Orders as the only forms of payment is another trademark, ESPECIALLY when combined with #1 above. Not only does he want to keep his bidders from being warned, he also wants a form of payment that allows him to take your money and deliver nothing in return with little or no chance of being caught. These methods of payment offer little in the way of traceability.
Also, WESTERN UNION HAS NO **ENFORCEABLE** POLICY ON WHO CAN PICK UP A PAYMENT. If you give them a name to use to "check to see if a payment is there" but not give them the passcode, they can easily make a fake ID that allows them to pick it up WITHOUT the passcode. NEVER USE WESTERN UNION! EVER!
3. If a high-feedback seller has been inactive for a long time then suddenly starts selling these high ticket items using one (or both) of the scenarios above, then that person has either hacked the account somehow, or PURCHASED the account at another auction. Yes, it IS possible to sell your Ebay identity after you've racked up 200+ positive feedback.
4. If a high-feedback seller has been recently active (i.e. has feedback left within the past 60 to 90 days) and all of a sudden wants **only** Western Union/Money Order/Certified Check when he HAS taken Ebay Payments/Billpoint/Paypal in the past, this is another indication that his account has been purchased or otherwise acquired.
5. Be careful with COD's. If a seller agrees to ship you something COD, do NOT pay ANY money up front. Doing so could mean you just purchased a VERY expensive brick.
6. Whenever possible, USE A MAJOR CREDIT CARD. They almost always reverse charges in cases of Fraud like this. DO NOT USE A DEBIT CARD WITH A VISA/MC LOGO THAT IS LINKED TO YOUR CHECKING ACCOUNT UNLESS YOU KNOW FOR SURE YOUR BANK WILL DISPUTE THE CHARGE!!! Find out ahead of time what their policy is.