Well, there's a chance it might just not be his thing and he'll never like them.
But if you think he has misconceptions about them, look at what music he does like and introduce him to something you think has something in common with other music he likes. My boyfriend automatically thinks 'Spinal Tap' when I mention Iron Maiden, doesn't like Bruce's voice as it was in the 80s, and really dislikes their more flamboyant 80s stage clothes and performances. I'm introducing him via more recent music like A Matter of Life and Death instead