Marcin, I think you are completely right in your comment on this topic. Our eastern neighbors continuously supply us (and many others) with desperate girls which ruin our reputation because most people can't discern between a Polish and a Russian woman by her physical traits. More then that, the ethical/religious atmosphere in Poland is completely different then anywhere behind the eastern border. In Russia prostitution and prnography is rampant (top in the world), what is in Poland is nothing compared to that (yes, probably because of the religious values, but also lack of history of such behaviour and social pressure). Unfortunately, other Europeans still equate Poland with Russia, although we are way ahead of them, after all we're in the EU and they are not.
I am planning to take a trip to Turkey and I was warned that I might be taken for a prostitute because I can be easily confused with a Russian/Ukrainian girl...
I do realize though that the situation abroad might be slightly different, many Polish people might desperately try to get a job in the UK or Germany and sometimes they think that prostitution is their way to liberation.
This kind of social lumping is a problem for many nations, Polish people are confused with Russians (or Ukrainians); Japanese/Korean/Taiwanese are confused with Chinese; Turkish are confused with Arabs.... etc. etc. All these stereotypes cause lots of anger and confusion. And think about it, is a Japanese person or culture similar Chinese? Or can you judge Japanese people based on what you know about China? Of course not, that couldn't be more different then comparing a Japanese person to someone from Spain.