Brick and mortar retail stores don't put lists of their customers up on the internet so that others can evaluate them.  The ebay feedback system is flawed in that malicious users can use the feedback system to leave undeserved negatives.  They can also use the system to email your bidders to 'warn' them that your item is a fake -- just so the malicious bidder can get a better price.  The malicious bidders can also send emails to other bidders to tell them not to conspire to not drive the price up too much.  This hurts sellers.

Your customer list should not be public.  Your bidders' identities should not be public.  Scam artisist send fake second chance offers to your customers or offer to sell them an identical item at a lower price.  Feedback and auction bidder identities should be private.  You can easily implement these tactics to ensure that malicious ebayers don't tamper with your ability to sell your items.

It's also possible that a malicious ebayer can email somebody who leaves you a positive feedback to tell him/her that he bought a fake or that he paid way too much for the item, and this can turn what was once a happy transaction into a transaction in which the buyer wants a refund and no longer trusts you due to the malicious email that he received about you.

Private feedback.  Private auctions.  You should implement these and you should inform your trading partners to do the same.