We are letting a room in our tenement apt in Glasgow. Currently we have two female guests, and today we discovered that a guy we don't know has spent the night with them. We find this unacceptable: the airbnb guests are registered with airbnb and have provided their ID, but this is some random dude that we know nothing about, and he now has access to our WiFi, has seen the flat from the inside, may have had access to the key, etc.
How would you react to this? I can see a whole range of possible reactions from our end, from doing nothing, to just changing the WiFi password and deducting a star for "unapproved guests", all the way to changing the locks and invoicing the guests. Just trying to gauge what others would consider appropriate. In the 4 years that we have been doing this, this is the first time this has happened.