They key to being a firearms instructor is to get students to learn. In a super macho sport like gunning, the really hard part is to get the steroid infused students to stop trying to show off for the instructor and actually learn the skills you are teaching.
Good instructors give credit where credit is due, don’t brag about and show video of the bad guys they have waxed, and they don’t tell you their way is the path to the gun god himself. They don’t even have to look like some covert, shaved head, tattooed operative.
Good instructors teach and make you want to learn. Its up to you to learn and then decide if their lessons will help you.
The best firearms instructor I have had the pleasure of learning under is Il Ling New. Not because she is a woman, not because she is witty (though that helps) and not because she hangs around my buddy Sheriff Jim Wilson. Nope, its simple; she knows how to teach humans to do things with guns.