SEN 5241: "You know I have a way with the computers. I can clear myself for any area."
(Oops, this isn't a THX 1138 thread. I'm mixing my metaphors.)

Privacy at eBay is a myth.
(There ... that's more in keeping with Fantasia.)

The eBay auction's Bid History shows the bidders (obfuscated by periodically changed anagrams). The links from the bidders shows their Bid History Details with a 30 Day Bid History. That's where you extrapolate their interest based on their submitted/pending bid-categories.

eBay's feedbacks are listed with user handles in the clear. Once the exchange has been made between seller and buyer, feedback left/received will reveal the user's actual handle. From there, you may be able to send an eBay message to that handle through eBay's Advanced Search of a buyer/seller. (I've never had occasion to go that far, but that's the procedure.)