Oh god, my hair was awful when I was drinking! It was really long but it was really greasy all the time and it didn't matter how much I washed it. In the end I cut it all off and bleached the hell out of it just to dry it out but my hairdresser still noticed it had this kind of icky greasy feel to it. I have let the colour grow out and am growing it now and it's one of the many pleasures of sobriety that I can touch my hair and not go 'urgh'. I can't say I've noticed a change in the colour because this is the first time I've had my natural colour since I was 12. That's about the time I started drinking so I'm using it as a kind of symbol of my sobriety.
I don't think it's shallow. My hair being gross was one of the things which really made me realise how much I was damaging myself. It came after a load of other health problems. With a lot of slap and hair dye I could pass but there was no way to hide how sick I was making myself forever.