Things like wrinkling, seeing light through, and light and dark sides to fabrics are great indicators of quality or lack thereof. BUT as you handle more and more fabrics, your fingers will begin to recognize fabrics with the perfect "hand" or feel for quilting.
I have actually bought fabrics that looked awful sitting in my stash and the minute I touched them I knew why I bought them. QQQ, Quilting Queen Quality - a feel to the cotton that transcends even its color or print. Of course, its much nicer when it's found in fabrics that play well with my colorways. Find a cheap fabric (like cheap cotton at Walmart or similar) and you can feel the rough, coarseness of the piece. Hint, some higher priced pieces feel similar. Let your hands teach you!