"People use to have the impression that avoidants are sloopy people, careless of their higiene."

Huh, really? I've never heard that before. I would think that because they are so scared of criticism, they take extra care.
One way I am different to a lot of women: I never wear any make-up - except mascara sometimes. I had a brief period in my late teens - early twenties where I bought some but I never really got into wearing it (and my skin doesn't like to be covered up)

Apart from that I think I might have cared too much about my appearance and let it get me down because I wasn't happy with the way I looked. I was very particular about certain things, for example I would only wear a skirt with heels because I thought my legs looked too fat otherwise. But moving to a different city has changed that and I'm glad I'm now more relaxed about what I wear.
I also used to spend a ridiculous amount of money on cosmetics - which I now prefer to spend on other things. My obsession about my hair having to be brushed perfectly smooth is gone, thank god! If I'm in a hurry in the morning, I'll just put it up in a pony tail and not care if it looks a mess. No one cares in this city, anyway. I don't think it means I've gotten careless though, I do still take care of my appearance and hygiene. I just stopped worrying so much about what other people would think, which I see as a good thing.
The hair dresser thing you mentioned I can relate too though, that is one thing I still put off for as long as I can for the same reason as you.