When I got my first job as an assistant professor, my office was one of the first ones students would see upon entering the department, and I liked to leave my door open. I was constantly deluged with students seeking forms, paper clips, etc, as they took me to be a secretary. Even after I placed a sign on the door reading “This is NOT the department office”, and giving directions to the office, the errors continued (though they dropped down to one a day). You might think this was just a matter of location. But after I moved to a new office (I was understandably eager to do so), various men had that office. None of them was ever mistaken for a secretary.