LesB,I think the vociferous emotional reactions to even just the tune, as you speak of regarding "Dixie" is very real to many people.
I can't stand "Oh Susannah" because I was taught to sing it in an integrated (black and white) classroom as a child, with the original offending words, and remember how some white children used those words to taunt one of the black girls in our class in particular with them. They regularly reduced her to tears, and I felt utterly powerless to stop them from taunting, or her from crying. I can't stand to even hear the tune, because it triggers that memory of my powerlessness, and hers.