i didn't write that, i'm just citing (unfortunately i don't remember whom)
English gives us a few contrasting pairs between nationality and ethnicity, notably with the -ish countries:
Spanish / Spaniard
Scottish / Scotsman
Swedish / Swede
Danish / Dane
Finnish / Finn
Polish / Pole
Turkish / Turk
French / Frenchman
Dutch / Dutchman
Chinese / Chinaman (not much used these days)
With Arab/Arabian/Arabic, we get all distinct adjectives for people, place, and language. :)
so there's no reason to be offended when someone calls you a Pole :/ It's rarely meant to be pejorative, from what I've noticed. Native English speakers I know tend to use it interchangabely with "Polish person".
Pollack/Pollock/other variant of spelling is disparaging though. It's quite "popular" actually, you hear it a lot in Polish jokes.
I didn't mind being called Pollack in jokes by my good friends - I would retort with a "Frog" to my French friends then or a similar "appropriate" epithet :) Depends on the context I suppose
btw about "holes"... "Dutch" used to be belittling too. This use still survives in fixed phrases like Dutch courage, double Dutch, go Dutch...