I have made it a practice, that whenever I have a SINGLE person booked, I always reach out to them to ask if they are coming alone or if they'll have someone else with them. Invariably, they have a guest, making it two people staying with me instead of one. This happens 9 times out of 10. I think part of the problem is that when the website asks for "number of guests" the person making the reservation thinks they are being asked how many guests THEY are having. THey don't understand to count themselves.
I wish Airbnb would change the booking parameters to reflect the phrasing "Total number of occupants" rather than "number of guests" because then there is no misunderstanding. I'm sure I'm not the only one this is happening to, but it happens frequently and then I have to justify the $10 surchange for each extra person. Have any of the rest of the community experienced this issue?