Not much of a clubber myself, but my friends and I did have suspicions that the bars were overcharging us in Warsaw. Many bars don’t have any kind of menu, so how would a tourist know if he were being overcharged. Our suspicions were more or less confirmed when we walked into a bar without giving ourselves away as foreigners, I walked to the bar and say “T-ree pivo.” I just nodded when the bar tender spoke, when he brought the beers and said the price, I just gave a bill that was surely big enough to cover. I counted the change afterward, and it turned out to be 3 zloty per beer, whereas the cheapest we got served anywhere else was 5 zloty. Coincidence? Maybe.
But the great thing about that trick is that once they charge you the cheaper price, you know the real price and they can’t charge you more once you start speaking english.