DB had a search on his top earning domain which was a very specific term. This meant that most of the people coming to the site would click on that. The PPC on this search term, however, was lower than the more generic terms on the page. So I suggested removing the specific term to see if the PPC would increase as people clicked on the generic terms. I would expect it had an effect on CTR which was hopefully compensated by a PPC increase.
Ed