My LQS doesn't have anything posted about photos and they frequently post pics of events and new items on their social media sites. That said, I'd feel odd taking a photo without asking. I assume they'd think I was going to buy it elsewhere unless I stated a reason for the picture. I feel that way at most retail shops.
I was recently out of town and visited a shop that had signs up saying that pictures were only allowed to be taken if you'd purchased the kit. That seemed fair. I really liked one but not the fabric or even the whole design - more the concept really. So I went to their social media site later and found it posted. I saved that photo to my hard drive for reference but wouldn't post it elsewhere.