If people set up their account with a Facebook log in, the airbnb wbsite takes pictures from that account, sometimes the first one, sometimes a dozen. Most new guests don’t even realse it, till you ask them if it’s deliberate.
I ask, if there are kids, more or less undressed persons or things that seem offensive. If it’s an error, they change it and are glad to be told, especially if the picture should be a private one.
Some people do it deliberately. I had a cartoon character once, stretching her bottom to the viewer. The guest was herself a host, with this picture! I said I think this picture is either an insult or an erotic invitation and I won’t host her if she did not change it. She was offended, said the picture came from a children’s book.
I don’t think she paid the copyright fee to use it...
I did not host her, airbnb cancelled the Instant Booking, but did not care if she used it as a host.