Shop,
Do a search by bidder:
http://search.ebay.com/ws/search/AdvSearch?sofindtype=3...ageName=h:h:fitem:US
Check “Include completed listings (last 30 days)” and “Even if not the high bidder”. After the results come up, click on “Seller” to get the auctions sequenced.
One other thing, do a “Search: Items by Seller” on the buyer. Check “Show close and exact User ID matches”. That will give you the buyer’s state. If it matches the seller’s, that may be cause to raise the eyebrows a little higher (I did that on this buyer/seller – one NY other FL). Obviously it's not foolproof, but people do some foolish things.
Of course, bringing up their feedback to see if they’ve exchanged a lot of feedback, or bringing up other auctions to see if they’ve retracted/cancelled, and checking out their registration dates. If a shill has a registration date a couple of years before the seller, then that must be one very patient shill, or a non-shill. If the buyer and seller have the same registration date, then take pity on the seller - he is shill-impaired.