I'm not sure how to find that info or I'd use it often. I bid on knives a lot but do not win and then see the damn things back for sale with the seller claiming non payment being the reason for re-listing.
Ok, now that others have pointed it out, I figured it out. Go to the auction Cheezy listed in the first posting. Click on the bidder count, so it goes to the page that shows the bidders. Yes, the bidders id's are masked, but you can click on the masked name, and it takes you to a history page that shows their 30 day summary of bids.
You'll notice that it shows that the bidders have
only bid 100% of the time on this particular sellers items.
Now, that
doesn't mean that a guy with feedback of say 316 over 14 years has
only bid on a single guys auctions, EVER. It only shows 30 days of history, so it's possible that during the last 30 days that bidder was only interested in 1 or 2 things, and they just happen to all be items that one seller is selling...
That still doesn't prove shill bidding, though I guess it could be an indicator of
maybe. Now if the history Ebay shows was much longer than 30 days, and the guy had only ever bid on his auctions, that would be a lot more proof and would make me steer clear of that guys auctions