Mucking crib

I just got a call with and unusual and probably useless question.
The question was. "Do you have to show the crib if you declare no points and muck it?" The point being, one player said that he wanted to be able to see how his opponent threw to his crib.

I suggested that the player with the declared zero point crib show his hand with a few points in it just to throw his opponent off. Jeeezzz.

I'd say that all cards should

I'd say that all cards should be shown at the scoring stage. For one thing, there might be muggins points to claim!