@Harold75 My second guest ever was a young woman who arrived alone, went into town for the evening, and then the next morning emerged from her room with a guy in tow. As I had just started hosting and had not yet found this forum, I was rather shocked. However, it was obvious that she wasn't trying to pull a fast one, as she immediately introduced me to her friend as if it was all okay, and when I said "You booked for 1 person and I only host solo travelers" she looked so shocked and crestfallen that I could tell she just assumed that if she booked a room, she could have another person if she wanted to. (she was brand new to Airbnb)
So I said "What, you're both going to squish into that little single bed?" They said, "Oh, yes, no problem". So I just charged them a bit extra and let him stay.
They were both really sweet kids and it turned out that they were "sort of" boyfriend/girlfriend but he had been travelling in Canada and the US for 6 months and was hitchhiking to my town and they had a tentative plan to meet here but of course he didn't know when exactly he'd get here. They spent everyday until about noon in their room but were quiet about whatever they were doing in there, took long walks, went out dancing at night, and were really quite lovely. Her review was brief but wonderful "I spent the best week of my life here."
So I'm glad I didn't make a huge deal of it, but it let me know that some people will share a single bed if you let them 🙂 Now that I'm more experienced, I make sure to reiterate when people book that it's only for one.