I think I get where he's coming from on the over classification thing though, it does get kind of annoying when its over done. Personally I like a few genres of metal Death Metal, Grindcore, Blackened Death Metal. I might talk about the questionable subgenres with someone when we're discussing similar bands eg ( Brutal Death Metal, Technical Death Metal, Blackened Death Metal ) but there is a definite tendency to take that too far.
I know I kind of kicked it off with the mall-core remark, but I basically reserve that for trendy fake faux-metal as loved by the combover hot-topic scenesters - you know the kids that discovered metal when they turned 14 last year and put their makeup on after they've left the house so mommy don't see, on the way down to hot topic to be seen with their friends, cut themselves, and shop for colored hair spray.
"emo"-metal, eh?
i hate to say it but seeing all the emo crowds around, i actually miss goth.