Respecting others opinion is professionalism at its best. Sometimes not challenging a customer's negative opinion about your favorite machine neither reflects your enjoyment of what you do nor your expertise in doing it. When you take a customers disparaging comment to heart, you risk losing your objectivity.
Customers, after battling a machine for a length of time, can also developed heartfelt feelings. I, for one, am not a washer-customer social worker nor appliance relationship counselor. Others may elect to be such. I will, however, repair their machine and educate them about it. If the customer still feels his machine is a piece of crap, so be it. I'm not a believer in the maxim "a customer is always right" , but I do subscribe to a principle found in How to Win Friends and Influence People, one of the best books on sales techniques ever written. That principle suggests when dealing with people, many times it's best not to be right...even when you are.
Source: Finished with KitchenAid