There is an interesting paper from John Morgan and Jennifer Brown of Berkeley which analyzes the Illicit “market for trust” on eBay. They onserved how on eBay there are a lot of listings with a Buy-It-Now option and a price of 1 penny. A Buy-It-Now sale for 1 cent automatically results in the seller losing 29 cents because eBay charges a 25-cent listing fee and 5 cents for the Buy-It-Now option. So, why should I sell something for 1 cent if this means I’m going to lose 29 cents? Well, basically I’m buying a positive feedback and paying it 29 cents. It is very interesting to note that the item being sold is actually a 1-cent “Free positive feedback ebook and recipe no shipping” which advised buying 100 different items on eBay that cost almost nothing in order to “get your feedback score up to 100 in just a few days.”
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(the image is from the same authors paper “Reputation in Online Markets: Some Negative Feedback”).
Does such a listing make sense? Well, it depends. The article goes on saying that the sellers, after getting a wonderful reputation, are probably going to move in very profitable markets such as selling cars or lands. For example, the authors found one particular seller, whom they dubbed the landseller, who had accumulated hundreds of feedback points by posting 304 offers for feedback enhancement on eBay (and losing $87.64). Then, after his feedback rating reached 598, the landseller went on to try to sell several parcels of undeveloped land in the southern U.S. on eBay.
This is one more example of a trust metric attack: every time someone provide a system based on reputation, some people will try to fool and attack it. No system is totally attack resistant. And this is uber interesting.