No pictures at all in the vendor booths but the quilt show quilts you can take all the pics you want. Funny: Last year one vendor told me no one wasn't allowed to stand and gaze at her vendor booth quilts. She said anyone could memorize the patterns and replicate them. I was admiring the fabric not the pattern but I smiled and spent my money elsewhere.
Oh be sure and buy the AQS Quilt Show Book. It has a picture of every quilt entered and all the info about it. Much better than taking your own pics. I tend to take a close up of a quilt detail that interest me. You are allowed to get very close but not touch the quilts.