Crumble the cornbread and set aside.
Combine the tomatoes, corn, and scallions and set aside.
Mix together the sour cream, buttermilk if using, and dressing mix. Set aside.
Layer the salad like this: ½ the crumbled cornbread, ½ the tomato mixture including ½ of any accumulated juices, ½ the crumbled bacon, ½ the dressing½ the cheese. Repeat. Cover tightly with plastic wrap and refrigerate overnight.