Well I don't necessarily recommend this
but when I was in college in a rooming house the landlady would just barge right into our rooms with prospective new tenants and their parents when it was close to a semester ending. One day a woman really WAS stark naked and heard the door opening and fortunately was able to jump into bed and pull up the covers! She said later if she had been sure it was just women entering, she would have just stood there and let the landlady embarrass herself!
But my roommate and I decided one day to leave the room a total mess. We hung bras out of dresser drawers, left the beds a mess, threw panties and other dirty clothes all over the room, left boxes of tampons, candy wrappers and stuff out in plain sight, turned over the trash can with trash falling out of it onto the floor, etc. We never did know if she brought anyone in during the day when we were gone but most likely.