"A Bangladeshi takes no offence at having what he has served at dinner verbally torn to shreds. In his mind he has shown hospitality and his guest is simply being honest." - according to Helen Rowe.
I would like to add here that there are some people who have a tendency to complain at everything, so its their nature to speak out their opinion and they seldom do it to undermine the host. Thats why the host is least bothered. And those who knows etiquette, try not to comment on the food, even knowing that the host would not have mind if he/she criticized.