More likely an Argentinian racing duck.
However...in my experience, unless an account has been hijacked by some unscupulous personage, a high positive feedback should indicate that a buyer or seller is good to deal with. Although I cannot quote the calculation method without going to eBay, your feedback score is based on the number of transactions you have conducted (both buying and selling?) in 12 months Receiving or giving positive feedback for good transaction experiences helps maintain a 100% reputation for the eBayer, making it more likely for other Ebayers to trust and deal with that member.
Of course, there are other wrinkles to it, but that pretty much covers it, I think. I make it a rule to post feedback - it is only fair and courteous. Having been a seller on occasion, and experienced a couple of disappointments, I do find the new restrictions very irritating - there are some right idiots out there (surprise, surprise) who need to be warned about.