I always wondered why it's impolite to put one's elbows on the table, or to sing at table. Seems like singing at table could be uplifting and festive.
I don't bother about the hats, like I said, unless it's obstructing a view. One time, though, I sat behind a lady at a bluegrass show whose HAIR was obstructing my view. I couldn't rightly ask her to take it off. But could big hair be considered rude?
I believe in the epistles of Paul, he said that men should go uncovered in church, and women should have something on their heads. This is probably where the whole thing started.