In Michelin dining circles, it is considered a great a compliment to be invited to visit the kitchen in any good restaurant. It is an expression of pride by the owner or manager to observe how the culinary skills and standards are maintained by that restaurant.

One should do this if invited: Refusal is usually interpreted as an expression of something wrong, suspect, or amiss by the patron.

If there is a celebrity chef attending the kitchen, refusing to view the kitchen might then be grounds for future "errors" in finding your reservation for the next evening, or discovering other subtle hints of displeasure like as a golf ball in your Foie Gras.