We have always charged an extra guest fee for any guest after the first one. It’s not been a problem in almost 300 stays. I do have to pay attention during the booking process. Anyone who books for one person who doesn’t explicitly say, “it’s just me”, is questioned about the number of guests they are booking for. When they tell me it’s really 2 people or 5 people or whatever, I have a response that I’ve perfected over time that I copy and paste to them.
It tells them what their actual price will be with the extra guests, the reason for charging per person (to give solo travelers and smaller groups a discount and to accommodate a larger portion of the Airbnb community) and that I will be sending a change request and that they are free to accept or decline, that I will understand either way and that they have 48 hours to cancel penalty free.
I’ve never lost a booking over it and have never had a complaint about it. I think you can file it under “how it’s handled”, like most things. Surely I have had some people not book because of it but that’s no loss to me, because we’re clearly not on the same page to begin with. It may even be one reason why we haven’t had any really bad guests - it’s easier to weed people out prior to booking than to get the reservation cancelled.
We get a lot of single travelers in our 2BR apartments. We love our single travelers, best guests in the world, but we wouldn’t get them by pricing for 4 guests. We also get a lot of couples who need separate beds who we’d miss out on by pricing for 4 guests.
Theoretically, but it’s never happened. And there’s also plenty of groups of 4 or 5 that are paying a lot more but hardly touch anything, so you’re covered either way.