"Polish jokes" mostly went in and out of fashion in the 1980s, if I remember correctly - though they certainly live on among some people who thrived then, I guess.

I would not generalize the use of "Polish" as a modifier to all of the USA. Although it's certainly hard to tell - due to the cringe-worthy nature of the usage stifling its usage in public! - it is most characteristic of the working-class Northeast. Well, perhaps in the Midwest, too. I wouldn't know. It's gotta be somewhere where there are actually Polish people! I grew up not far from New Britain, Connecticut, which is one of the Polish Diaspora centers of the US. Once a week we ate kielbasa, and any community meals usually included pierogie, kluski (sp?) and gawumpki (sp?!). But out here in California, few people are aware of such things. Even to use the "kielbasa" elicits blank stares. So to say "Polish" in any off-color fashion would brand you as a bigot.

Of course, Californians have "Mexican" as their go-to ethnic/national term (though it does not equate with Polish). "Mexican standoff" is perhaps one similar concept. A more accurate equivalence: What we call a "Puerto Rican shower" in the Northeast US is a "Mexican shower" in the West, I believe.

I grew up calling fingerless gloves (the kind you wear outdoors to keep your hands warm, while retaining the ability to do fine work) as "Polish burglar gloves." Yep. Hardy-har-har. But I don't think it was about trying to be clever/funny, since the "joke" was too old and conventional. I get the feeling that such usages are more about affirming social class. That is, the "upper" classes, bereft as they are from Poles, etc., would be worried about the reaction from saying such things, whereas the working class folks (among whom you'd invariably know and interact with some Poles, etc etc) "don't care."