It seems to me that in the shops I go to, both the chain stores and the LQS, the clerks are trying to do a conscientious job. I just expect some shrinkage and buy a little more than I need. Some patterns will state that they are allowing for shrinkage and the yardage given is generous, so that's another consideration to look for.
This thread reminded me of something we were taught in sewing class in the dark ages. When you bought new fabric, you not only washed it (which at that time might have still included wringers in some people's homes, followed by flapping on a clothes line), but when it was almost dry there was one more step: You would get a helper and the two of you would pull the corners to get the weave back into proper alignment. Apparently, way back when, that was just the norm, but store clerks who didn't cut carefully along the grain could expect to lose business.