You'd not mind receiving a quick phone call a couple of hours before the appointment so say "sorry love, I'm a bit knackered today so I'm just gonna have a kip instead"?
Well, that's not how it would go, is it?
Not if the prostitiute has a brain
The call would be something like, "I'm really sorry, but my child is sick and I've got to go and pick him up from school. I know this is inconvenient for you, but could we re-arrange. I'll give you a bit of a discount, and sorry again"
If you got that sort of call a few hours before the booked time, any experienced punter could put plan B into operation.
And, yes - I'd rather that than a shit punt because she's knackered.