I actually got insulted when I saw the subtitles, but my mom explained that people in other parts of the country wouldn't have understood. Most of the time I have no problem--but I think there are a few people I've met here who deliberately
do not want to be understood by all.
The strongest Southern dialects do
have influences of other languages, though. The Cajun accent of Louisiana is French and African-influenced, and other accents are African-influenced as well. Further complicating matters is the suggestion some people have made that a little bit of Elizabethian English is still in the Southern accent (i.e. from Shakespeare's day). How true THAT one is, I'm not sure.