Where it comes from
The format is as old as massage sold beside harbours, which is to say very old, and every port city has run its own version under its own vocabulary. What varies is the honesty. Bangkok wrapped it in spa language, other capitals in classified-ad code; Amsterdam, which had already decided in the seventeenth century that desire priced openly causes less trouble than desire denied, simply put the words on the menu. We inherit that habit of saying the thing, and guests tell us the plainness is half the relief.