I'm new to both eBay and Brickset. Could someone clarify precisely what the risks of purchasing Legos on eBay are? Is it simply that the item may not be shipped or may not match the details in the listing? I scanned the lengthy Announcement regarding this but it seemed geared to folks already in the know. Any clarification of the risks as well as ways to discern the fraudulent from the authentic (they can't all be bogus, right?) would be appreciated.