Also Dutch courage (artifical courage from alcohol)
& Dutch uncle (a term describing someone who provides "tough love" type of advice, harsh but well meaning criticism etc)
Isn't it amazing that these wars have found their way into the English language?! I mean, when were these wars? 17th century yet you can still find traces!
I can't think of anything that entered the Dutch language because of the Anglo-Dutch wars.
I haven't heard any proverbs in Holland connected with Poles yet.
Come to think of it, the Dutch also use the expression "Poolse landdag", similar to the German "Polnischer Reichstag" and the Swedish "en polsk Riksdag".
But all in all, I don't think they should be called "insults" as such. I don't feel particularly offended if Teffle accuses me of talking double dutch ... ;) It's well-known anyway, isn't it ... ;)?