Sellers cannot leave negatives or neutrals for buyers, and if they leave a positive rating with a negative comment the buyer can ask eBay to remove it; the seller then gets a Policy Violation.

If you open and close non-paying bidder cases, the bidder gets a strike. Members with 2 or more strikes in a year can be automatically blocked. And are by prudent sellers. far more effective than leaving negative feedback, even if it was possible.

I swear eBay really need to do a Sticky thread on feedback so it stays at the top of the buying and selling boards..

as a seller with about a hundred transactions completed, you surely know
Sellers can not, leave a negative fb.  been that way for several years now.

had to open up cases and relist this item 3  times when we look at the buyers feedback they have 100% positive comments but 90% are negative

You are copping all the deadbeat buyers that nobody else wants. You need to protect yourself from the habitual non-payers...

Go to My Ebay > Account > Site Preferences > Buyer Requirements

Switch on all the blocks in there, set it to block people with 2 or more Non Payment Strikes in teh past 12 months. Tick to apply this to your existing listings, then click SAVE.

Now, providing other sellers have reported the non-payers like you have done, you won't get these time wasters stuffing up your auctions.