When a child folds his arms and diverts his gaze while talking to you, it is out of respect, not defiance.
A Vietnamese will likely to offer you a portion of her meal before she eats it. It is an insult to offer afterward. One gives the dogs the leftovers.
No matter how far you have traveled to visit a Vietnamese home, the first thing the family offers is a drink and a bath. This is so you will feel refreshed, not because you are dirty or smell bad.
You never disturb someone to ask him to do something while he is sitting down at a meal. You are disrupting a very personal, reverent moment.