Charlatans Forever

My novel is divided into two parts, or eras. The first era is set in the 1920s, and the second era in the 1960s, when computers come on the market.
My novel, or story, shows that no matter what the era, scammers and charlatans use the same tactics: lies (big and small), theft, shamelessness, and a tenaciousness in their criminal behavior that is almost incomprehensible to the average citizen. We recognize these traits in our modern-day politicians.
But what, exactly, is a charlatan?
A charlatan is perhaps more dangerous than the usual scammer because he/she believes in their products at a certain level while their rational mind rationalizes their criminal behavior and lies. Their lies and schemes easily envelope the people nearest to them. They have elevated IQs too. In essence, they can think circles around the average citizen. They have no real friends, just acquaintances that they can use.
Lastly, the \ch\ in charlatan is pronounced as \sh\.