Ethical search engine optimisation gone wrong
Chris Heilmann's article Ethical search engine optimisation my foot! is a story of what can happen when a client brings in an SEO consultant to improve search engine rankings.
While the changes to the site the SEO consultant requested may well have improved search engine rankings, they also hurt usability and accessibility. And this was a so-called ethical SEO consultant.
I suppose I'm lucky, but I've been able to talk most of our clients out of using SEO consultants, despite the aggressive marketing they use and the excessive media coverage some of them are getting.