I have to admit if I have a choice I am more apt to go for jeans/shorts or at least comfy pants and a nice t-shirt. In that same category though I VERY seldom go out in just sweatpants and a sweatshirt as to me they look (or better yet how I look in them) is just messy.
And make up and hair are not as important to me... make up for special occasions (or when my face really decides it wants to break out!) and my hair in a pony tail to keep it out of my way is the norm.
Now, if I have someone to dress for, who appreciates the effort and the suffering that is a different story. Basically at that point I almost become an entirely different person.... because there is a REASON to suffer. Just as Tom enjoys seeing women in uncomfortable clothing I am more willing to tolerate the stockings, heels, extra daily time for hair and make-up for I know it will be appreciated and not just overlooked.
I don't necessarily feel that makes me vain... just makes me want to please who I am with!