Imagine person A is staying in a hotel in Paris for a month. During this month, a friend, person B, comes to visit person A for 10 days and stays in the room A is staying in. The hotel is fully aware of this fact and has even requested the ID of B when he arrived and granted him a key for his ease. Person A is paranoid and explicitely asked if B staying over would change the amount she is being charged for the room. The hotel said that no, that this fact is not relevant for them and that the price stays the same as if B had never come.
When the 10 days are finished B leaves the hotel. The question is, does B have to pay the city tax before leaving, even though the room is reserved for just one person (in this case A)?