Did you bid on his auction before reading his feedback?
If so you can Retract your bid. Go to the site map, bid retractions are in the lower left corner.
Did you bid and win?
You can ask the seller for a Mutual Cancellation. This will release you from the transaction and you can leave feedback.
If you won, but do not pay, the seller can open an Unpaid Item Dispute. If you do not pay, you will have a Strike which will make it harder for you to bid on eBay. However, if he really is a scammer, he may not want to call attention to himself.
Did you pay?
It can take up to a month for your item to be delivered, depending on where it starts.
If Day 30 has passed, you can open an Item Not Received dispute and get a refund from Paypal. If the item arrives after you have been refunded, you can repay the refund using Paypal's Send Money service.
has a ton of negative feedback already.
What are the percentages? If a seller has 100 sales and two negs, that's high. If he has 100 000 sales and 500 negs, that's fairly low.
Any percentage under 98% is a red flag.
What do the actual feedback say? If there is a consistent pattern of 'not shipped' or 'poor quality' that is useful information. However, sometimes it is obvious that the buyer is nuts or illiterate. The seller's Responses also tell you a lot about his committment to customer service.
If a seller is getting 'too many' negs, eBay will remove him. There are millions of sellers on eBay, but you can put him on your Favourite Sellers list and watch to see how long it takes for him to become NARU (Not A Registered User).
