I usually "pseudo CCW" in that I'll have some sort of cover garment but not try too hard in such places. For example, a jacket tied around the waist or an untucked shirt with obvious printing.
Never been hassled.
Of course, I usually prefer to avoid such places altogether. Even if the signage is not proper or doesn't have the force of law, they've made it clear they don't want my business, so why should I give them my money?