Yes, it is a violation of their rules, however, nothing can be done until the sale is concluded and the defrauded buyer files a claim. Ebay used to reveal the identity of bidders during the auction, but they are now hidden by aliases, such that they cannot be contacted to alert them before they buy. The only time eBay will get involved while the auction is still active is in cases of trademark infringement, such as fake Gucci handbags and designer jeans. In those cases, eBay is liable for damages by the owner of the trademark for being a knowing conduit for a fraudalent transaction. When it comes to antiques and obsoleted products, they are not liable and simply do not care. To them, it's a case of caveat emptor.