So I booked a number of hotels recently via Booking.

Hotel1: only has one room in total in the category we wanted to book. It's a very small hotel with 8 rooms. A few days later both the hotel website and various booking portals still mention there is still one room available.

Hotel2: When I booked 1 room of that type was still available. That was still the case yesterday. Now it's gone.

Hotel3: booking portals mentioned 3 villas left, after booking it's still the case.

Hotel4: 1 room left before booking on hotel website and portals. Still one room left on portals, hotel website changed - can't see how many rooms left.

So, how do portals do that? Are availability numbers fake? Do they buy additional rooms if numbers get low?

Thanks