There are any number of objective and subjective ways to know, the restaurant just needs to care about it. Off the top of my head: - actually eating the food f

There are any number of objective and subjective ways to know, the restaurant just needs to care about it. Off the top of my head: - actually eating the food from time to time - checking orders before they go out - checking orders after they are done, to see if food remains - checking yelp and other reviews - being a chef and doing chef-like things