There are more of those sorts of arrangements going on than you know of. Usualy it happens after the girl has moved in and can not pay all the rent for the month, then an arrangement is made to offer services. I have even heard of one situation that where the owner sold the building and the renter complained to the rental board that she was able to pay with services previously and the new land lord would not honor past deals.
I have been told by SPs and MPs that they offer services to the land lord as a bonus for allowing them to do business on their premisis.