I can tell by the way a person stands, sits, or walks whether or not I can talk "freely" or not. People who wouldn't say $#it if they had a mouthful hold their chin at a perfect 90° to their chest all the time, sit with both feet flat on the floor, and walk like their heels are sore. They seldom wear hats, and if they do it will be incredibly clean and straight. Fingernails PERFECT. If there's a beard it is neatly groomed.
Even if you keep your vocabulary in check they are still judging you, either by the vehicle you're driving or the cleanliness of your shoes.
The real jackasses are the ones that ask permission to pet your dog. What the hell? Look at him! By all means PET the sonuvabitch!