Is the look and feel of a product pleasant? Does the commercial's punch line work? Are customers accepting the product?
These and many other questions are answered in market research, in product and UX testing. Among the tools and methods of market research are customer surveys based on questionnaires.
The challenge is that direct and unadulterated reactions of the subjects and emotional effects are often not taken into account.
In order to offer your customers the best possible service or the most excellent product, however, you need to know exactly what customers want and how to adapt your offer accordingly.