You wouldn’t realize it, but Southern folk have much in common with the people of France. They both elected Jacques Chirac, they both connect to England via the Chunnel, and they both have the most extensive railway system in Europe [*citation needed].
And much like the snotty French, people in the South think they’re too good for English and have decided to create a different vocabulary. For example, not only is “mightcould” an acceptable word (as in “Yer car’s busted? My cousin mightcould fix that.”), I’ve also heard its antithesis used (as in “oh, I just remembered that my cousin hates you, so he mightnotcould fix that car.”) If at some point in the distant past someone mightcould, but is sadly now is unable to, “usetacould” may be employed (as in “My cousin usetacould fix cars, until that idjit went and got his arm ripped off on a carnival ride. Bless his heart.”)
Which brings me to the “bless her heart” rule. “Bless-her-heart” is like a vocabulary corrective. It’s a powerful insult panacea. You can say the cruelest thing about anybody, and provided you say “bless her heart” after the insult no one has a right to be angry.
It’s strange, having to learn a new language just to be able to communicate in my own country. It’s almost insulting, coming from a place where everybody speaks normal English like normal people.