Probably people who don't think of their homes as red-necky hicksville backwaters.

I do agree that you should find yourself comfortable anywhere in the country with common sense. I wouldn't go dancing with a boy at a road house or start making out anywhere. You'll be fine.

I don't mean this in a derogatory way, but small towns are culturally different than larger cities (that's neither good nor bad). You'll find many similarities and many differences. You should exercise the same consideration any world traveler would in a different culture, respect the differences, and proceed carefully.

BTW, I have spent a lot of time in small towns across the country, and I have two relevant observations:
(1) There's not nearly as much difference as you'd imagine amongst small southern towns, small northern towns, and small western towns.
(2) I have found charming, accepting people in towns small and large and I've found bigots in both as well.