Curious - we've seen the ads and heard the claims, so:
What percentage of electricians/plumbers/specialists/contractors/construction workers out there actually sign up to be 'found' and 'reviewed' and 'background checked' by these services?  I've asked a few guys that we've had work done from here in Estes (new roof, replacement windows, outside paint job), and they have more work than they can handle already and they all said they have not signed up in the Angie's List/HomeAdvisor world.  

{Same question about how many dealers have signed on with those 'magic' no hassle/best price used car sales apps we see commercials for ...}