Hmm, then next time I suggest throwing in the phrases "groan metal", "transition metal" and "technique metal" to see if you can catch them off guard*.
*These might already be metal genres, who cares!
(also, chav metal, eyebrow metal, homeless metal, diseased metal, anaphlactic metal, metal metal, life metal, birth metal, prebirth metal, adolescent metal, geriatric metal, historic metal, andalucian metal and, well, the list could be nigh on endless)