Much like the other guides on retaliatory feedback, I think it grossly unfair that eBay will not involve itself in disputes for negative feedback left to purposely ruin another member's reputation. In fact, I would go so far as to day that eBay are neglecting their duty in providing the auction site service by not actively helping to resolve issues.
I had a 100% positive feedback until a new member recently left retaliatory negative feedback. I always state in my listings that a non-payment strike will be made for failure to pay and appropriate negative feedback left for the non-paying member. The buyer did not pay so I did as I said, resulting in retaliatory feedback. I also received abusive emails via the eBay website, which were reported, yet not investigated.
I think it highly ironic that eBay will swiftly investigate and threaten suspension for any fee dodging listings yet allow new members, who have little or no reputation to lose for acting badly, to damage the history of a respectable member.
I would like to propose either a provisional member system, whereby new eBay buyers/sellers cannot leave negative feedback unless a minimum number of transactions have been made. Or, another option would be to have voting buttons, much like the seller ratings, rather than leave creative feedback which is open to abuse.
I only leave feedback once I know that the other party has received the item and is happy with their purchase. I now hesitate to leave negative feedback because of my retaliatory experience, which I hasten to add is only one of a handful of unsavoury experiences. However, there does seem to be an increasing number of members who misuse and ruin eBay for others which needs to be addressed.