The sites making the most "per click" are not focusing on keyword lists, they are focusing on providing value to the visitor, and putting the visitor in a position to make a purchase or sign-up for a service, etc. They are converting visitors into customers for their advertisers. That is why they are making the big bucks per click. Not because the title of their blog has some big expensive keyword in it. Just my opinion! Read the full blog post here
I don't think that is the only thing that goes into the CPC earned for site. I think a site that converts customers more easily will earn more per click than one that does not. At least that is what I see with my sites... ;-)