"I doubt that booking even happened"...
Simple then, describe the room the booking took place in, and others who have been there will either recognise it or not.
It's easy to descrie a few peculiarities about a particular location that others would recognise, i.e. what floor was it on, what colour front door, what colour bedding, was it one or two bed, bath or shower, toilet in bathroom, colour curtains, colour carpet / bedding, obviously not all of that detail but you get the idea, any genuine punter who made a visit to a location would easily be able to establish he visited.
I'll give you an example of a flat myself, Smiths & Steve2 know, I'd describe as follows
Above an electrical shop, enter via metal staircase at the back, then walk accross a flat roof, down a couple of steps accross to another metal staircase and up about 6 steps to the white PVC front door, two doorbells, odd as there's only one flat there. When waiting for the door to be opened you overlook a car lot opposite, the door lets you into the kitchen then left down the corridor, bathroom on left, seperate toilet, bedroom then a couple of stairs and two further bedrooms. A bar type glass fronted fridge in the room with cold cans of dring in it.