It seems 30 years ago there wasn't as much of a difference in quality of fabrics as there is now, although quilts I made 30 years ago do have some fabrics that are so thin they've come apart at the seams, and no one wants that to happen.
This being said, quality fabrics definitely have a nice "feel" about them. Sometimes LQS's can get a line of fabric that doesn't feel like top quality--so I always trust my instincts and the feel of the fabrics before buying them. And once in a while you can find better quality fabrics at JoAnn's, but you really have to be careful. If the fabric feels stiff or rough, or has a looser weave that you can see, it's probably not going to last and these fabrics tend to also fade over time in the wash or by light.
When on a budget, it's hard sometimes to justify spending more money on fabric at the LQS, but remember "you get what you pay for!"