I'm of the impression that proper southern cornbread is the version without sugar (as well as cooked in a preheated cast iron skillet that goes back into the oven), whereas northern cornbread has sugar. (Wikipedia mostly agrees, at least on the sugar front).

This caused me problems when I tried to make cornbread on my own for the first time after moving north for college. It wasn't as good as I remembered from home until I realized I had to take out the sugar.

We are in our cornbread!

In terms of things like "sweet tea" or Pepsi, that's very true. But having grown up in the south, and still living there, I've never known it to be commonplace to make cornbread sweet here. There's also a deep divide among southerners on whether BBQ sauce should be sweet or not.

Personally, even being from eastern NC where vinegary based BBQ rules supreme, I prefer the sweeter style of BBQ. YMMV.