Just to go back to the original purpose of the thread, I think many metal fans adopt the image not completely for love of the music, but for a sense of belonging. Some also maybe to "fit in" or to be individual... which of course is bollocks as you aren't individual if you look like every other metalhead.
Basically it shows you are part of something you are proud of, as MM said for some it's a lifestyle, but that invariably leads to others adopting it for just the image etc. etc.
But that has little to do with anything, it annoys me when people judge on image, metalhead or not, and seeing the majority of metalheads claim image isn't important to them it just shows how it really does matter
As for my image, I wouldn't say I'm particulally metalhead, or much else for that matter
But at the same time i dress quite extreme - normally I have a shirt (today with flames on
) and tie with some large trousers and boots (today these also have flames going up - newrocks rock
). Which I'm happy with, and I think that's what's important, not what others think.
And I'm happy for several reasons, firstly I have very wide ranging musical tastes so I feel guilty wearing band tshirts which are invariably metal (others are too hard to get) when I listen to just as much non-metal as I do metal. Secondly I like people's innability to pigeon holes me as goth, metalhead, alternative, greb or whatever, and thridly because of that often people are often uneasy because of they can't just write me off as one thing.
And I should be revising hence me bothering to write all the above