So this morning I was thinking about how my own Metal Points™ system would work, and realized that there was an entire subcategory of Metal in my mind that I had no name for... Until it hit me. Or rather, I almost hit an old 60's van that wasn't very well taken care of. Rust™.
Now, what qualifies as Rust™? Any song or musical element in the genre of Metal that I feel degrades MY overall enjoyment of the genre. This includes, but is not limited to, screaming, guitar parts that make my ears hurt because everyone is playing full chords on identical Marshalls with 0 mid-range, and gargling hot asphalt.
Now, just as the rules for Rufus & Twitch's Metal Points™ change from time to time to suit Rufus' whims, my rules are not hard and fast. There are times that gargling asphalt works. See Marco Hietala in Nightwish, or even Disturbed's David Draiman. They find appropriate points (usually) to break out a tar and gravel mouthwash and are able to still hit notes that are pleasant to the ear while simultaneously sounding like their vocal cords have been paved.
So, until I find a better term, anything Metal that does not strike me as pleasing or a reasonable difference in opinion is Rust™.
EDIT: Wrong -tucky...