You would get the couple and they wife would say.. here's some ideas for you and other times people would would completely scan their camcorders over your stall.
If you go to Camden Lock market their are stall doing designer club wear and there are large notices saying no photography allowed.. don't know if that would be a good idea for the crafters here.
What ever the case it is best not to get argumentative with people as it only drains your energy.