Most vendor booths do not allow pictures of their sample quilts and some won't let you stand and stare too long at them! I found a few in Paducah that would notice someone standing too long looking and they would interrupt them. No kidding! Too easy to recreate the pattern and not buy it.
The big quilt show quilts are always open for pictures. The only quilt show I went to that did not allow pictures of the quilts was a local guild show. The President didn't want others to copy any patterns by taking a picture. Everyone of the quilts were from patterns easily found, not one original one in the bunch. Mostly Bonnie Hunter's free patterns. I asked her where the original designs were that had to be protected and she said well our work doesn't need to be spread around creation. LOL.