How can you buy a good Yelp rating?

There are reports that Yelp ad sales people claim if you buy advertising with them they can make bad reviews go away [1]. Of course, it's possible the sales people are just claiming that to make the sale and don't actually deliver on it.

There are also people on ebay [2] offering five star reviews for around $15.

[1] http://www.eastbayexpress.com/oakland/yelp-and-the-business-... [2] http://www.ebay.com/sch/Web-Computer-Services-/47104/i.html?...