If it is the sellers you left negative feedback for, that is not the way you use feedback.
If you are not happy with a purchase, ebay put on every listing a link to the money back guarantee. You use that to open a Not As Described Case to get a refund, then feedback is left to reflect how the seller dealt with a refund.
Just jumping in and leaving VERY VAGUE negative feedback would make you a first choice for sellers to put you on their Blocked Bidders list.
