TRAVEL POLITELY Dear Heloise: My husband and I recently returned from a lovely trip to Europe. For the most part, it was enjoyable, except for a couple of embarrassing moments that were not caused by fellow Americans. We were in Germany when a man from the United States started yelling and insulting the young man stamping our passports. He brought up World War II and made all sorts of ugly accusations. Finally, his wife grabbed his arm and told him to be nice. The airport security was called, and things just went downhill from there. As an American, I was appalled by the man’s behavior while h…