It's pretty simple.
You cannot advertise or sell vaginal intercourse.
Anal and everything else, nobody cares.
Soaplands and others get around the vaginal service in the manner of selling you a bath (or admission to a bath) or social services of a woman (or man). They are not advertising or promising you vaginal sex, so completely legal. (otherwise it's a don't ask, don't tell situation...)
You (the client) don't face legal issues by using any service of course unless you abuse or attack the provider.
The burden of proof is heavy and as stated before, the legal issue falls upon the person receiving the payment for a service.
If you are bothered by it (or any legality), then please stay away from the business and save yourself the worry.