Absolute lack of interest in foreign (Polish) culture, etc.
Unfortunately it works both ways, we can't blame only Germans.
For Poles in general, the only real interest in Germany is among the lower classes, people who consider emigrating there permanently or temporarily to earn money. If a Pole is slightly better off, he/she is much more likely to be more interested in Italian or French language or culture, there are people who love Ireland, UK, Czechia or Hungary; also Spain, Croatia, Greece and Turkey are popular tourist destinations but if someone says that he is going to spend his holiday in Germany, they are going to get a lot
of strange looks.
I suppose it's still the consequence of WW2. I am 44 and I remember what my grandparents told me about the war and occupation; I grew up with those stories, so it's still a personal thing for me. Younger generations might have a different attitude, hopefully.