How should a monk address subjective questions?

Suppose a monk is invited to a house for food and the lay person asks how the food is? How does a monk reply to such a question. I am sure a monk in his lifetime comes across many such subjective questions. How should he deal with them? Does he: 1. Just reply something to satisfy the lay person 2. Give him/her a teaching on impermanence of everything From the stories in Buddha's life, it is clear that he laid great emphasis on timing his teachings to someone. Many a time he would say that this is not the right time for him/her to learn the Dhamma. Having this in context, does it make sense to impart teaching at every possible opportunity. Please incorporate any stories if any to showcase the tradition.