There's no wrong in asking, of course. I believe all asked, if you didn't even ask how much she cost for that night, then prepare she might quote you some rip off price.
IMHO,
Nego kicks in if you were quoted, i.e 6K฿, and knowing that the actually price is 5K฿. Again there's many factors why she quote you 6K฿. She probably just trying her luck, to earn more, or she don't want to go with you hence the 6K฿, and so forth.
Again nego with the after you being quoted 5K฿ is not wrong, but probably will kill her mood off. Knowing that she can earn 5K฿, if she rejected your offer.
And some might just got death fish, she can just feign shes tired, like it or not there's nobody you can complain too. And for this case you probably just leave her alone or just pay up the 4K฿, probably after spent time 2hrs or so.
There's so many reasons to type, but this is a few factors to consider. Therefore why would you want to risk you happiness over 500฿.
But you quite smart, I read in one of the post you always took ST before LT. But again if you playing thai girls long time, you will know. Always expected the unexpected.
I'm not sure where you from, but if you said that the girl that looked hot is not a cup of tea for the Japs then probably not my cup of tea either. Hence I believe only in your eyes she's pretty, and that's the reason you got her for 4K฿.
So I now without assuming I shall say you not handsome.
Sorry to burst your bubble. LOL!
Yup they got choice to choose, but given the situation there's no customer for that night and happen a fat guy came for you, will you reject him cause he is fat?
Well it's bad for you then. There's no guarantee by paying more you will be satisfied. BUT I believe for those who quote high price themselves will provide good service, why, its matter of time before words spread around that you giving lousy service and you got nobody to serve after that.
David read back my replied you about your look. Those were sarcasm.
And just to let you know the DP isn't me, it's belongs to one of the sbf police.