I have hobbied for many years but never visited a studio. I wanted to visit Barbies, but one of the problem was that I could never speak to the girl and get any confirmation on the menu.
When I called the lady who picked up the phone gave me an impression that the fee is just an entry fee and everything else is at the discretion of the provider.
Which meant that there is a risk that when you enter the room, everything is an upsell.
This is not so much of a risk with Asian SPA because they have a very fixed menu so there is less chance of YMMV.