Well, I think that many singers sometimes just sang what they felt like that night, and many times the words might change a little from time to time. Plus the fact many songs were sung from memory from the way they thought they remembered hearing someone do it. Until not too long ago the words were not written down so it was all from memory. Cajun music also seems to lend itself to add libbing.
I love the way Dewey Balfa sings Jolie Blonde on his recording with marc Savoy and D.L. Ménard on the LP "Under a Green Oak Tree. His words are slightly different as well. Ever heard it? It's worth a listen.
About my favorite version of Jolie Blonde is Dewey singing it during a live performance in New York with the rest of the brothers and Nonc Allie Young. The only place I have seen that recording is at Cracker Barrel restaurants.