Makeup isn't bad for skin. If it was it would be disgusting altogether. It would have a cumulative, negative effect like smoking, or any other bad habit. The worst thing you can do is not remove it well at night. That's where makeup can be gross but it's not exactly designed to be worn without removing it. There are mineral makeup a you can sleep in, but that's another point.

I'm in Paris at the moment and the air is shit. When I don't wear make up, I break out- when I do my skin clears up because I have a nice barrier from the elements and I've got on 15-30 SPF in my products. I also remove the make up and exfoliate and use all sorts of awesome products. I've got one face that I plan on keeping for my life- I don't want to look like an old paper bag so why not take care of it?

Makeup is actually beneficial to wear and should be treated like food. Good food= better nutrition . Bad food= bad health, etc.

You also absorb makeup in your body so yes in many ways, makeup should be treated like food. And thus, like food one should also pay attention to expiration, brand, etc as factors that must be considered for ones benefit. You don't want to use old spoiled nasty stuff and the best way to tell is by smell and by skin patch tests.

I've always thought makeup is one of the coolest things invented. In another life, I would LOVE to learn how to turn people into monsters in movies for special effects. Anyway that's all I've got to say.