Final answer:
The quote about customers being the best salesmen does not have a clear author but represents a common business belief in the value of customer satisfaction. In contrast, ADM's president's quote reflects an adversarial approach to customer relations.
Step-by-step explanation:
The quote 'We figure our best salesman is our customer. Treat that person right, he'll walk out the door and sell for you' does not appear to be directly attributable to a known individual through publicly available sources. Instead, it seems to be a general business principle emphasizing the importance of customer satisfaction and word-of-mouth marketing.
However, contrasting this customer-centric perspective, the president of Archer Daniels Midland (ADM) was recorded in an FBI sting operation stating, 'Our competitors are our friends. Our customers are the enemy,' a view that reflects a more adversarial approach to customer relationships, common within cartel operations. The correct understanding and practice of customer relations are crucial for a business's success, with many companies recognizing that a happy customer is the most effective promoter of their product or service.