http://searchenginewatch.com/article...cks-on-PPC-Ads
We've been focusing on exact match domains in both adult and mainstream for eons and sell a lot of them - mostly to buyers getting them on SEO basis or domainers getting them to resell on that basis, but as this study showed, they help in other ways too.
I think even with more and more spammers/scrapers trying to abuse them and people running into exact match domains with crappy sites, when they see exact match, they subconsciously think "relevant" (Google's bolding of them probably helps too).