No matter where I go, people mistake me for an employee. They approach me and ask me if I work there, where they can find things, or other similar questions. I answer them if I know the answer, otherwise I usually just try to send them in the right direction. They usually get apologize, saying, "Oh I'm sorry, I thought you worked here." Every once in a while they add, "You just look like you know what you're doing." (I look like what? lol)
Anyways, I usually wear Khaki pants, so I think this is part of the reason for the confusion. Most of the time I wear either a button down or polo shirt, but a lot of times it's not something that looks anything like the uniform of the place I'm at when people ask me if I work there.