The rather large commercial sex industry in the Czech Republic has long been known about by people in nearby countries such as Germany and even further away in the United Kingdom. Although there are no go go bars or soaplands with neon flashing lights, there is a lot of prostitution in Prague. The sheer amount of Czech porn available ought to give you an idea. Prostitution is legal in the Czech Republic. But there are restrictions. Things like pimping are illegal as is the case over the border in Germany.
Still there are plenty of commercial sex venues that operate openly and even get visited by law enforcement regularly which bring the laws relation to actual practice into question. There are stories of guys being overcharged or ripped off in Prague strip clubs going back decades. The women who work at these strip clubs are usually not the most attractive in the city by any means but they do tend to be local Czech women in their twenties and perhaps thirties. Services are rendered as promised even though it is all typically done with a professional feel.
While it is more common in countries like Austria and Switzerland there is one proper sex sauna in Prague. That is Sexy Sauna Erotic Club which was reviewed on this website. Located in an area laden with adult entertainment the Sexy Sauna Erotic Club operates more or less like any German sex sauna though it is slightly more subdued and significantly more expensive.
As with any FKK the sauna is filled with nude women hailing mostly from Europe who lounge around waiting for customers. The place is large and has a hot tub, bar, lots of televisions and things like an open bar and free food. There are only two red light districts in Prague and they do not operate on the traditional model.
In famed red light districts like De Wallen in Amsterdam or Miari Texas in Seoul are basically districts where sex is sold out of shops.
