Don't talk to sales people, they are the devil. If you act like a sales person, people will think you are the devil. Labeling people is detrimental to good relationships. It is a bit like saying "all blondes are dumb" or "all accountants are boring". If you label people, you are the devil.
Sales people can seem like the devil. So can entrepreneurs who are too focused, marketing strategists who don't connect well, working mothers who are over their head or someone who is having chronic health issues.