I don't know if it still is, but used to be common in some Eastern European countries following the end of communism.
Prague, East Berlin, Dresden to name a few places where I've seen it.
Typically two or three 30-year old bottle blondes, sitting at the bar on stools drinking fizzy "wine" from a special bottle tightly controlled by the head barman.......in reality it was mostly soda water with a splash of wine. The girls would be intercepting rich looking blokes and inviting them to buy the girl a drink (i.e. fake champagne from the special bottle) with a view to moving on to more....
Also the head barman would be taking phone calls, jotting room numbers onto notes and passing these to whichever girl had been requested.
Nothing hidden, but at the same time not made obvious. The barman was the pimp, but whether he was acting for the hotel, or his own pocket is anyone's guess