I absolutely agree, and not just southern accents, ethnic ones too, Poles, Italian and the Irish (that subtle anti catholic thing) are often uses as a short hand for dumb. It has become political incorrect to use blacks, but there is a long history of that, too.

And its not just here in the tv capital of the world-- Monty python (which I loved!) used "Irish" to equal stupid--as did Fauwlty Towers---remember O'Rielly? Do you think maybe he was Irish? (stupid, lazy and incompetent all rolled up into a name!)
and if you have Scotsman about, sure but he is canny--so when you want a show with a quick witted, mechanical inclined hero, you got McGeiver!
Yes TV has some wonder moments, but it has been miss used!


my other obsession