Nearly all WGs like to spend the first 10 minutes talking so that they can get to know the punter and feel relaxed.
For goodness sakes, use that 10 minutes to go through with her all the services you require and note her responses. If she replies enthusiastically and affirmatively and her body language is good, you know you'll get what you asked for. If she "umms" and "errs" or looks her away to avoid eye contact or her body language is stiff then you know it'll be a bad 'un.
If it is the latter case, do not give her any of your hard earned cash, say "no" and leave or if you can't say "no" to a woman, say "I've left my wallet in the car" and leave. Every, and I mean this, every WG in the country knows that if she hears the "Wallet in the car" excuse, it means that the punter is not coming back so never, ever feel guilty about leaving a girl in that way.
Of course, if you give the girl the money straightaway or before you've satisfied yourself that you'll get the services you've asked for then the only word apt enough to describe you is: "Plonker!".
If you think with your dick then you have no one to blame except yourself.
I honestly have no sympathy for such men.