It's often more than just the words themselves or the way they are delivered that make such a difference, though. The first example that came to mind is Thersites's and Achilles's speeches in Book 2 of The Illiad, where Thersites (a lowly, uncouth, and ugly soldier) says essentially the same speech (in mostly the same words) as Achilles--one is well received and the other is not, but the difference wasn't strictly in charm.