((Note:: Part of this is due to Dave's comment about a guy being so metal that if you stabbed him with a knife there would be sparks or something... I couldn't find the statement when just looking.))
((Note 2:: These are some initial thoughts. I'm free to change my opinion at any time.))
To be metal, does not involve any fashion. It does not involve long hair, denim jackets, leather, band t-shirts, nor does it involve how you decorate your wall, nor how much you can drink. You don't even have to listen to metal exclusively.
To be metal, is all about the attitude. Metal is as much about emphasizing individuality as it is about bringing people together in an very non-conformist way. Thus, in the same way, a person can be metal in a very individual and non-conformist way. To be metal, then is to have the attitude of individuality, and non-conformity. It is to be a person who questions the tired ways of society, never accepting them just because one is supposed to, or just because its the way its always been done. A person who is metal often has a longing and deep hatred for the current condition.
Just as metal musicians often try to push themselves into musical excellence, so would somebody who is metal push himself into excellence in whatever he chooses. Because it is in excellence, in the action of pushing the envelope, that one enjoys freedom.
The reason a large number of males in the metal scene have long hair is because of the same reason that hippies did. Hippies enjoyed long hair because it wasn't accepted. It was a rebellious act. Metal, the same. Even today males with long hair are looked down upon. It gives that 'wild child', 'unprofessional' look to some. Personally, I really can't grow long hair. My hair gets to look really crappy when it gets longer (as far as I can tell, based on when my hair grows out a bit), and my hair just doesn't seem to want to get long. Anyhow, the clothing is just another part of identity, and showing ones love for metal. Its also again, by wearing a metal shirt you are saying 'this is who I love' and since metal is a rejected part of culture by the masses, its announcing that one doesn't give a fuck if you don't like what they listen to, and that one is a member of the rejected culture. But as I said, you don't have to have long hair and wear metal shirts, nor denim jackets to be metal.