Why do they do this? Destroys both their reputations.
Because it is difficult to walk away when one is out on street with an urge to unload. This is how many brothel setup b&s work, when asked during booking they confirm that a particular WG is available and make the punter come all the way.
I concur, I'd say try to have a plan B or mentally prepare yourself to walk away if you don't get the right SP
The game is to get you thinking with junior as opposed to your head, bet Rose got herself some clients with that trick.
Personally it's been tried on me twice but I fought my corner & got the right SP in the end, but I'd rather they don't try playing tricks.