Prostitution (Prostytucja) in Poland is legal, but operating brothels or other forms of pimping or coercive prostitution and prostitution of minors are prohibited.
Whilst the red light area around the train station is rife with unauthorized street prostitutes, the legal stuff takes place in "massage salons" or via escort service agencies.
There are approximately 2,000 prostitutes in Warsaw.
Specials such as two girls cost of 400 - 500 zł (100-125€).
For an all-night meeting have to pay from 1500 to 2000 zł (375-500€).
This kind of trap has happened to many tourists so you wouldn't be the first one.
Naturally if you're very drunk, this kind of situation will appear much more likely than if you were sober. They’re simple enough to find, just look for the flyers pinned to car windscreens or clogging up the gutters.
Also, if you don’t have that amount of money on you, they’ll be more than happy to escort you to the nearest ATM to get the cash.