The JoAnn store near my house is pretty big, although more space is devoted to home dec stuff, floral, and other crafts. They do carry some better looking fabrics, the Kona I got there recently was actually less ravelly than the stuff I got at my LQS. Yes they do have some pretty ratty stuff, but just as much good stuff.
I also make clothing, and I have noticed that most of the clothing fabrics are polyester, although I got some really nice linen / rayon blend at a good sale price.
But I go there most often with my coupon, seems to be a personal goal for me to own every ruler every made. I also get a lot of books there, my Joann has a really large quilting book section as well as a pretty good selection of knitting books. I have noticed that magazines are always 10% off so you can never use a coupon for them.