Americans are so polite   All that “Mr President”, the gracious ante-bellum South, the way their troops in WWII always wore their shirt-sleeves down,   the prevalence of “Sir” and “Ma’am” not only from a maître d’, the way musicians brought on stage are introduced as “Miss” or “Mister”.   Americans may swear in bars but, for today, I’m held by how a young black woman, seen on YouTube, pulled over for a missing light,   is saying by her boyfriend’s body: “You shot four bullets into him, Sir.”   Geoff Page Be advised   Be advised, you smoochy duos,…