I'm not really sure if red hair should be an alias to redhead. A lot of the times I'm looking for things like post #165737 or post #260104 and all I get is pages and pages of Asuka, Kallen, Misty, Asuna and all kinds of other stuff that would be better served with orange_hair or pink_hair.
The fact is that "redhead" is a kind of natural hair in the real world and such characterization has no place in anime due to the existence of characters with actual red hair.
Right now, the tag is virtually useless.
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