Over the last year I have given a fair amount of coverage to PayPerPost, who now house the service along with other endeavours under the name Izea.
There are multiple reasons why I have supported PayPerPost and similar programs so strongly, and yet at the same time have never reviewed a link buying / selling service.
I have mentioned link buying and selling in passing, and also a couple of Wordpress plugins, but those plugins generally allow you to sell links which have a nofollow.
My emphasis both in editorial about services and in the few reviews I have myself written is to encourage the writing of quality content with editorial links. Compensation in whatever form should be based upon the time involved, expertise, and possibly the size and influence of the audience, and not based upon any SEO benefit to a site or service being reviewed.
