Jag Lady wrote:
 I might also add that Southern has made its way into my speech, though a Southerner could pick that out in an instant.

A little different from what you are saying, Liz, but, in movies/TV, I can usually tell if someone is doing a fake Southern accent -- even if they are really good. There is a certain cadence that is hard to capture if you are not a "natural born Southern speaker" -- I imagine this is also true for other accents in other parts of the country, as well.