Despite their lack of shame, in what ways are the Duke and King clever and knowledgeable about human nature? Why do their scams succeed so well?

THeir scams actually don't work out. They do for a time but these two push things until they are found out. THey are good at acting and, to the masses who want to believe, they have a way with people. THey are kind of like slimy used car salesmen who are really good at cheating people. They are both entertaining and seem to have a chemistry together until things go wrong.