Such an obvious generalization may seem ridiculous but it is no laughing matter for salesmen. It's what you have to face when you sell your services. Almost everyone has doubts about anyone trying to sell him something. Salesmen have acquired a bad name in general. There is no way to please everyone.
People are that way.
A salesman is in an awkward position. Sales persons get to face Man at his worst behavior. Most prospect aren't even aware of their rudeness in a situation like this. I doubt it. At least the economy would be much weaker.