I've been watching Ebay for diesel pusher Motorhome listings, and yesterday saw one that looked too good to be true - a 36 foot Winnebago Chieftan, supposedly offered by an east coast doctor - the selling price was $16,900! 
The giveaway was the note in the listing that instructed responders to contact the seller DIRECT at an email address provided in the listing. I emailed the address given, and was given this response from the "seller":
Hello there,
Since this too sounded funny, I ran a search on the email address of the guy supposedly selling the MH - and got a lengthy list of other scams of this same sort, with the following explanation:
YUP - it all fit my situation perfectly - be warned, if something looks fishy, or too good to be true on Ebay - STAY CLEAR!

The giveaway was the note in the listing that instructed responders to contact the seller DIRECT at an email address provided in the listing. I emailed the address given, and was given this response from the "seller":
Hello there,
Thank you for your interest in my Winnebago Chieftain . I want you to know that I closed my auction earlier because someone offered me the buy it now price, but didn't have all the money available and I cannot accept financing. The price I want to obtain for the car is $16,900 US (this price includes shipping and insurance charges).
The RV is like new, completely working, perfect running condition,with no hidden damages or accidents,it has always been garage kept, low miles, non-smoker no flood or storms. It is a US model with US specs and passed the US test emissions. It will be as if purchased locally. The Chieftain is insured in case of damage and you will receive it to your address in 5 working days . It will come with all the necessary papers (clear title, bill of sale, warranty documents, user's manual,insurance etc). The title is clear and you will be able to register the RV in your state without any problems.
I am requesting a $2,900 refundable deposit at the beginning of the shipping and the balance to be paid after delivery and inspection. If you are not 100% content with the Chieftain you will be able to ship it back on my expense to get your deposit back. I am sure this will not happen, because it is a state of the art vehicle and you will have no reasons not to be content with it.
We will use eBay Motors as third party. First you will pay the down payment to eBay and you will send the receipt proving your payment to eBay. Please note that eBay will hold your deposit of $2,900 until you will confirm that you received the RV and you transferred the title into your name.
If you agree with these terms, please send me your full name, home and shipping address, eBay ID so I can register the transaction with eBay asap.
... waiting for your fast answer, Dr. Alexander Johnson.
Since this too sounded funny, I ran a search on the email address of the guy supposedly selling the MH - and got a lengthy list of other scams of this same sort, with the following explanation:
Thank you feedbite.com for this fantastic RSS tool! This RSS feed bundle is designed to warn eBay shoppers of Fraud and Scam auctions on eBay. The auctions are uploaded to hijacked seller accounts, but the auctions are fake. How does this happen? - seller falls for phishing email and gives his login credentials to scammer - scammer takes control of legitimate sellers account, quite often with very good high feedback and uploads anywhere from 1 to 1000 scam auctions for high end popular items : vehicles, antique cars, motorcycles, tractors, cameras, expensive electronics, popular event tickets such as Disney or Season Tickets... . anything that sells for over $500 ... - one thing the scammer usually does not do is change sellers contact email address because eBay would alert the account owners original email address that there was a change. - SO THE FAKE AUCTIONS ALWAYS ADVERTISE CONTACT TO SOME EMAIL ADDRESS... usually disposable free email accouns at gmail.com hotmail.com msn.com aol.com and yahoo.com
YUP - it all fit my situation perfectly - be warned, if something looks fishy, or too good to be true on Ebay - STAY CLEAR!