As a tourist in Thailand, usually, you will not be able to pick up a "good" Thai girl. If a Thai girl goes with you to your hotel, then she expects payment – even if your name is Justin Bieber or George Clooney.
There are, of course, exceptions; however, the above applies to more than 999 out of 1,000 cases. You are probably not the exception!
In Thailand, it is not customary to have a casual sexual relationship except when money is involved. If you want to have sex with a "good" girl, you will have to court her for a longer time, and probably with a chaperone, the first few times you are together. You will never get to have sex in the short time before your holiday is over.
The traditions are slowly changing among young people because of the influence of the West; thus, if you are young and appealing to a Thai and you hang out with young Thais at a disco in Bangkok, then maybe you can pick up a girl the same way as back home. Maybe!
Otherwise, the girl expects payment in one way or another.
The girl may not mention payment; typically, Thai girls are shy in this regard. This is especially true of those that have a regular job and just want to earn a little extra in their free time; however, even those who have sex for a living may be too shy to mention money. On the other hand, she may not mention a price in the hope that you will pay her more than her usual price.
With no talk about money, it is easy for you to believe you picked up a girl for some fun like at home. In addition, if you are the one out of a thousand, asking her for a price would be a disaster.
A solution can be to place an appropriate amount of money halfway under her bag in the morning. If she is not in it for the money, she will not take them; however, you can be pretty sure she will take them with a big smile. Up to that point, she has probably been nervous about how she should let you know you have to pay.
Please note that even though she does not take the money, it does not necessarily mean that you have picked her up for free sex. Some girls play the long game; they may be looking for a sponsor to flee or marriage.
It happens that one of the professionals gives away a freebie. Typically, if it is an older girl that wants to have sex with a younger guy. Pay her anyway. The time she is with you means she cannot make money from being with another customer.
Of course, the above does not mean that you cannot have a real relationship and true love with a Thai girl. Only, it takes more time than what you have on a short vacation. This is the case whether you want to find a "good" girl or whether you want a girlfriend experience to evolve into a real relationship. You will need to spend more time with her than what a single holiday allows.
Many tourists have married a Thai girl where the relationship started with money exchanged for sex. Some live happily ever after despite the girls past; others find out that the girl was playing the long game and only wanted his money.