Very few people angry enough to leave negatives just state not happy. They usually say something false like Seller was very rude or Seller accused me of not being honest, something like that, under those terms you can have it removed, especially if there has been no communication with them except the UPI. Mine was like that and I did have communication with the buyer and I still got it removed by Ebay because it was considered abusive (and it didn't even have swearing in it). You also have the ability to reply to feedback and state the truth as well if the person just writes not happy. Many do read the neg feedbacks to see exactly what the issue was (I know I do) and unreasonable people can be spotted a mile away because their feedback is vague or unrelated or not reasonable (for example a listing for something like beads 3mm, and their negative feedback was 'the beads were so tiny', which the seller could have fought to have removed technically).
