I have seen people rude by being over-polite.
Michel de Montaigne, Marvin Lowenthal (1999). “The Autobiography of Michel de Montaigne: Comprising the Life of the Wisest Man of His Times : His Childhood, Youth, and Prime : His Adventures in Love and Marriage, at Court, and in Office, War, Revolution, and Plague : His Travels at Home and Abroad : His Habits, Tastes, Whims, and Opinions”, p.97, David R. Godine Publisher