Marketing made mistakes in the past by relying too heavily on customer surveys and not understanding unconscious customer reactions. In the 1950s, marketing spread widely but has since fallen from grace. Modern marketing sins include overconfidence without competence, complacency, and irrational superstitious beliefs rather than relying on data and understanding customer behavior. Marketers should strive for excellence, integrity, understanding patterns and principles, and focus on supporting good actions while preventing bad ones.