it is because u are assuming the woman is 'honest'
u can be the most overcareful man:
if the girl wants u to pay, she will lie saying u took advantage on her
Let's be honest: even if u have 'agreement' to make love,
the PUA dont tell to the woman that he is a PUA: meaning some women can have more expectations (maybe they want LTR; or whatever)
We can also think that some women can be vexated they gave their ass to someone who 'lied a bit' to them (when they realize the PUA is a PUA)
==> some women are very mean when they feel insulted, betrayed (or whatever)
My point is:
in all ur comments, u assume this: "if i do it in proper way, everything will be fine"
it is not that simple