Above all they are practical. No fancy marketing. They have a sense of humor about themselves and often a resident cat. They may be good or bad but they are usually the only choice for many miles around. They often have a little restaurant with two mismatched tables and no two chairs alike. The donuts and such are probably made there and the owner immediately knows you are not a local.
The menu chalkboard may hang on a chain with two sides and gets flipped to the ‘tourist price’ side when they see a strange car park out front.
They may sell shoes, over the counter medicines, tire repair kits, reading glasses and ammunition all off the same shelf.