Is the customer always right?

Is the customer always right?

How do you want your staff to respond when the quality of your product depends on the manner of preparation, but the customer wants it done a different way?

Take for example a speciality coffee. Served piping hot the flavour is compromised and a skilled barista would never recommend letting the milk burn as it changes the natural sweetness, giving a bitter flavour. However, quite a few customers prefer their drink to be served 'extra hot'.

Any attempts to educate may be seen as condescending but if you are passionate about your product and want your clientele to appreciate its authentic taste, what do you do?

Do you risk offending them and offer them a comparison? Or just accept that the customer is always right?