Another one: they're in uniform, carrying a clipboard or other gear, and checking merchandise on the shelves, but, no, they don't actually work there, either. They're on the job, yes, but they're just a delivery person, or some other third party checking inventory in some capacity!
Ugh, I've been that guy too many times. I often do inventory at the bar where I work, which requires me to actually step behind the bar. So people come up and try to order things from me because I'm behind the bar, and I just want to wear a big sign that says, "I'm not really here! Don't look at me!"


(In my defense, he had his back to me, and was wearing the same colour shirt that the staff in that supermarket wear.)

Maybe she was too intelligent and saw through your compliment.