Just to confirm about Specialized, the fitters are sent on a one week training course on Specialized's fit system and have refresher courses every year or so after that. They also have to sit a test to gain certification. It's the same for Shimano certification (for workshop repairs) and no, not everyone passes.

But also ask for reccommendations as well in your local area. I also like "independent" fitters who don't work for a bike store (or work independently for the store) as they would be less likely to be "pushing" their brand of bikes.