Fool me once, shame on you! Fool me twice, shame on me!
In yesteryear, it was often said that a man's handshake was as good as a contract, that his word was his bond. (Pardon the gender-specific reference, but that's how it was said.) A promise was as good as gold.
For generations, we relied on a firm handshake and good eye contact. You didn't trust someone who didn't know how to shake hands. A “dead fish” handshake was not to be trusted and set the relationship off on a bad footing.
Integrity was the foundation of relationships, both personal and professional. They didn't file lawsuits in the old West. They pulled out their guns. You didn't dare steal a horse, lest you be branded ...