My buddy Steve contracted with Jeremy Hopkins to teach him to handle the 36 foot sailing yacht he chartered. Jeremy learned his craft in the Royal Navy and he's got papers that will probably let him captain an aircraft carrier. He's charming, and more importantly he can teach. It's in his manner actually, he's one of those people who not only loves what he does, but shares the passion - y'know what I'm sayin' here? He teaches by letting the student do. Impressive.
I like this triptych ... it's nuanced to say a lot about the guy's seriousness, charm, and humor. Add in competence and well... character matters, eh? And it's that kind of strength that can turn a student's resolve into action. Which gets me back to the teaching point.