Most unhappy customers never tell you. They just stop coming. Here is how to hear them before they go.
For every customer who complains, there is a room full of people who simply left.
Silence is not satisfaction. It is the most expensive feedback you will ever receive, because it arrives as a number on a report months after you could have done something about it.
Make it easy to be honest
Ask a smaller question. Not "how was everything" but "what is one thing we could have done better today." Specific questions get specific answers.
Close the loop out loud
When you change something because a customer said so, tell them. That single act converts a critic into an advocate faster than any campaign you could run.
Building with people. Not for them.