Hi Bob,
In all of my E-bay experience I have never seen a private user ID. I have seen private feedback (which still allows you to see # of positives & negatives for the user, just not the actual comments).
So I did a search on their Community answer boards. Seems that the seller sets up the auction as hiding bidder's IDs. You the bidder, can make feedback private but not your ID. The several threads I read indicated that sellers hide bidders IDs for various reasons. The obvious one being they are selling 'adult' items and want to encourage bidding by the 'shy' person. The second is that the seller doesn't want other sellers soliciting the bidders on their auction with the same or cheaper items. The third is to hide the fact the seller is 'shill' bidding up his own auction.
Don't know about anyone else but this auction with a brand new seller and zero feedback would take one HUGE leap of faith to bid on esp. @ $400+! Plus no pictures, plus hidden bidders.
Most E-bayers responding to the private user ID threads stated that they steer clear of any of those auctions.
Donna