Interesting news item tonight, from which I see that a fraudster has been hauled up before the Courts for shill bidding on eBay. The article contains a nice little quote to illustrate how much they claim to be spending to conteract fraud on the site, but it's still very much a case of "caveat emptor" and always has been - or at least for as long as I've been a member. The plain fact is that the buyer shoulders virtually all the risk over what is essentially a pig-and-a-poke, and the practice of partially blanking other buyers' names so you can't tell who they are makes dodgy dealing very difficult to spot however suspicious you may be. I suspect the guy who got caught was either greedy or careless or possibly both.
It does of course give a bad name to the majority of sellers who are honest and conscientious: certainly I've had some real bargains, as well as fair treatment as a regular customer - all of which counterbalances a proportion of duds from idiots out to make a quick buck for little or no effort. It hasn't put me off buying anyway, and I will say that on the couple of occasions I've had to claim refunds recently, I got my money back both quickly and easily.