Yes, and knowing something about the origin of the stupid polock jokes makes me want to vomit when I hear one.
Now this is interesting, Julie - what IS the origin of the Polish joke? I was just having a discussion with an English guy about the fact that he'd heard that most racist jokes in America were directed at the Polish. I told him that 25 - 30 years ago, I remember that being true - Polish jokes were all the rage, but for the life of me, I can't figure out why - as in why THEN? Why was it so big in the early 80s? And what IS the origin? I'd always just assumed it was the latest in the "insert ethnic group who's trying to assimilate here" strain of joke telling, but the Polish in my area seemed to have been there for as long as (mostly) anybody else - I never understood it.
Also, for better or for worse, I do practice the "I'm Irish, therefore, I'm allowed to laugh at Irish jokes, if they're delivered with love," principle, but trust me Sarah - the second I hear a racial joke delivered with anything BUT love, the teller earns nothing but my HATE.
Having said that, a good example of what you were talking about regarding the non-necessity of having a specific ethnicity in the joke is one I remember hearing as a Polish joke when I was a kid, but for Lubec, we'll put a different spin on it:
"Did you hear about the Moncton municipal league hockey team? They drowned in spring training." (rim shot!)
And as you say, that particular joke's effect is not contingent on the specific group of people it's directed at - Minnesotans could say it about Iowans, Northerners could say it about Southerners, etc., and vise versa.