Private listings can look suspicious but are not necessarily so.
Usually used for items of personal nature or collectables.
I don't bid on private auctions as I like to see if there is potential shill bidding.
The problem is you don't know if friends or relatives are bidding even if you can see the other bidders or not.
But with a private auction you cannot see the percentage of bids with that seller.
Do you refer to the bidder names that you can see?
For instance, other bidders will look like this to you: n***a (102
) 
Initially, bidder usernames weren't hidden on eBay. Then trust and safety issues were raised, when underbidders were being contacted with fake "second chance" offers. At that point, eBay began hiding bidder usernames with "bidder1", "bidder2", "bidder3", etc. But this raised other questions such as bidding history no longer being transparent.
That led to eBay's current masking algorithm. eBay hides the username of any bidder, by replacing it with a "masked ID that consists of two random characters from the member's User ID", separated by three asterisks
domeau.jwsqjrk, your username is also hidden in the same way from other eBay members when you bid. Each member can only see his/her own username; all other bidders will be masked. To assure yourself of this, log out of eBay and look at an item number of an item on which you bid; you'll not see your username there, but a masked ID.
Countess, I think OP is referring to private auctions, usually for sensitive personal items.
