A landlord's tale - who knew?

Dealing as I do with many a landlord you do come across some weird and wonderful stories. This one takes the biscuit. Everyone knows that the ingenuity of landlords is legendary. Let's face it, it has to be with all the changes that are going on but here is a story that takes some beating and demonstrates a tenant's chutzpah is as great as that of his landlord. Tell me what you would do as a landlord if this happened to you?

Tenant is fantastic - always pays on time and the landlord has never had any problem. Until one of the neighbours phones the landlord to say that there are a lot of people coming and going. Landlord thinks nothing more of this given the fact that the tenant is a student. Neighbours comes back again and says this is all very odd with the different people keeping coming and going. The landlord's interest is peaked by this and he decides to look on Airbnb just to see if the property was being sublet. And low and behold there it is. His city centre property is being advertised as a "Double Room in Cozy Flat Near City Centre" on Airbnb with - wait for it - 23 reviews and the best bit is that they are offering a 5% discount for a week's stay. Here's one of the reviews -

"The flat looked like in the pictures. It looked fine but slightly dirty in some areas. The keys to the building were a bit hard to use, which caused inefficiency, but this was not Vanessa's fault. XXXXXXX and her roommate were nice people, and gave many good tips on things to see and good places to go out in Glasgow."

So what would you do?

1. Serve notice as against the terms of the lease?

2. Admire their ingenuity and keep them there?

3. Raise the rent or seek to share some of the profit?

4. Book the room and turn up just to see the faces of the tenants as they try to explain what the hell they are doing?