If you call a hotel at 8pm they have vacant rooms what if you offer them half price to stay? Will some of them ?

Probably. Don’t expect the big chains with minimum staff to do it. They’ve got their set prices and a full board rate will help to subsidise some of their less popular locations. But some of the little guys might help you out but you might have to throw something in as part of the deal though. Everyone’s struggling but it’s worth giving it a go. Some of them might do if you pay cash and it’s off the books; especially if they hate their boss. They might impose some restrictions on you as well by asking you to vacate earlier than usual. And they’ve still got to pay someone to clean up after you; unless they’re planning to do it themselves. It’s also a judge of character on their part. You can expect to be turned away so don’t get too aggressive; especially if you still need a room regardless.