I used to do this, but recently I (somehow) got kicked into the upper tier of Booking.com’s genius program. The 20% discount you get by using B.c in that tier is unbeatable - I’ve actually had hotel front desk staff in multiple countries over the last few months tell me straight-up that they can’t price match that low and I’d be better off just using B.c.

Same here. I often tried to get s better price by just asking, but more than once the booking price was already far better than anything they could offer.

I never, and I mean never, got the genius welcome cocktail they always advertised for. No hotel ever heard of that

This is actually true with many online booking systems, especially the ones people actually use. I've been told this using at least 10 different booking sites at over 20 hotels since 2005. At one major chain in downtown Cincinnati the clerk brought the manager over, who looked at the rate, and proceeded to pick up the phone and contact corporate to adjust the rate up, they manager told me they were losing money at that rate.

I wonder how they can be losing money on a room that would be otherwise vacant?

Turning over a room (to make it habitable for a next guest) costs wages, and that's just the bare minimum cost that I can think of. There are probably a dozen hidden costs associated with allowing someone to stay in a room.

Yeah, I used similar site to booking.com last week, and asked the hotel if they can price match (they had best price guarantee on their site), and they straight face told me they can't ... baffling

Just remember that they will list hotels as «full» if they don’t have any rooms out on booking.com. Many hotels never do, and some hotels only do when they have a lot of free rooms.