Selig and his friends have done some excellent work at the speeds and sizes we fly at. However a lot of extra care to ensure the results were usable had to be taken. In his report published in Soartech8 by Herk Stokely there's a whole chapter devoted to calibrating and modifying the tunnel to work with acceptablly low turbulence at "our" Reynolds numbers.

However a lot of the older NACA material is suspect unless they get down to Re's of 200K or so. Often they didn't and the results at the higher numbers can be very misleading if you wan't to use it in a slower flying model.