The winning bidder has failed to make payment and has ignored my invoices and all messages.   Dispute/resolution is already in progress.  This buyer has 300+ positive feedback, and I feel justified in leaving negative (can’t believe they don’t already have some negatives) but what is to stop him/her giving me a negative just to be nasty and vengeful?  Do sellers just let it slide sometimes?  It makes a mockery of the feedback system.