[blatherard]

I think it depends on the joke, really. If you made a joke along the lines of "those nazis think they're hot stuff but you know what, they're POOR! They can't even afford to go to college and many grew up in POOR families!" I don't think that would be funny, even though I hate nazis, because the humor is based on dislike for a particular group of people. Not nazis, but poor people. "Nazis suck because they're poor" is the meaning. And that's punching down, even if the nominal target is nazis. Laughing at that joke is laughing at the poor for being poor and that sucks.

If the joke isn't related to the poverty part then its immaterial, and you're just making a joke about nazis, which is fine.