Some hotels physically don't have single rooms even if they can be booked so. The towels, soap, shampoo and so on are always for two guests. I'm not a wasteful person, but I wonder if I'm allowed to use everything in the room.
I guess, hotels don't care about that matter too much, however it is ethically important to me.
P.S. I'm mostly interested in 3 or 4-star hotels.
