Right and wrong ways compete for our thinking to get what we want in life. A salesperson's knowledge tempered with grace permits that person to help a buyer decide why and what to buy.
But when influenced by a greedy or a self-centered spirit, that same seller must clothe himself in distortions, half truths, and out-and-out lies just to close the deal. It is not that selling is an ignoble profession; it is more that ignoble salespeople stop trusting in what is right to convince a prospect to buy.
Young children, before someone introduces them to corrupt ways of responding to life; seem naturally inclined to take the 'straight path'. As they watch older children who watch parents--who watch The Jones who watch their bosses-- only then are young children tempted with the notion that lies and cheating are also options in life.
Watch this video: Cheating in Middle School.