> many hotels started using drop in guests as people to be hustled

It all depends on the approach. Instead of saying "do you have any rooms available?" you could just say "I only have $AMOUNT and quite frankly I'd rather stay here than at my old Uncle's place down the road" (or a variation of which indicates 'price does not matter'. [1]

Disclosure: I am somewhat of a paid professional negotiator so techniques like this may not work if not done properly or in every context.

[1] In another business you'd be surprised at how many people simply say 'can you do any better' (which means 'you have the sale') rather even 'wow that's to high... a competitor will do it for $AMOUNT can you match that?' Edit: Emphasis on a convincing use of 'wow!'.