Howdy Elfwithgrace & all Irish (Suthurners & Northurners),
Yeah, I think many stereotypes (though not as much superstitions as they are misconceptions or over characterizations), go back to origins in class struggles between aristocratic city dwellers of high society verses the common agrarian peasants or plebeians thought of as an underclass. A struggle that seems as old as time itself, but is richly flavored with great dramatic reality when considering the historical American South and the English / Irish struggles.
Stereotypes often have a core of truthfulness, but can get stretched to ridiculous caricatures. Most of the American South (or the Appalachian remnants of such) was originally colonized with common Protestant Irish stock and criminals (or more properly, debtors) who represented a disenfranchised society. The Republic of Ireland (and its split with England) is representative of this same tradition, even though it religiously remains predominantly Roman Catholic (which represents a disenfranchised British class).
The American South Irish were mostly the rich Protestant Irish throw offs from their upper class society. As such they were (and often still are) considered ignorant and backward. Oddly enough to some, but of no surprise to these keepers of good honest salt-of-the-earth wisdom, they actually (much as the Jews of Jesus day, amidst the power and moral decadence of the Rome Empire) are representative of a moral foundation of society that is often disenfranchised and taken advantage of, but is truthfully the only salient reason and justification for society. Far from being ignorant, they represent a spiritual selfless wisdom and earthy hard working know-how that is often lost to the wiles of higher education amidst some historically aristocratic elite who lack a use for personal egalitarianism.
This is why the American South is at once known as the Bible Belt, noted for their genteel hospitality, their stubborn independent spirit, and their common & charming wisdom packaged as good natured humor with a drawl; but also caricatured as ignorant and unworldly backward.