There's no denying that a good makeup artist makes my job...let's just say, less demanding on the post-production side of things. A great makeup artist can go far beyond that to really enhance the beauty that already exists.
I happen to know a great makeup artist. Her name is Ashley and she does some magical things with an air bush.
To me, makeup is very similar to photographic lighting in the sense that you dial up the drama on the parts you want to feature, (eyes, lashes and lips) and tone down the detail on other areas. (pores, blemishes, freckles)
I was fascinated to see the entire process, so I got together with Ashley to do a time lapse of her working. There's not a shred of retouching in this video and when I saw the first and last frames beside each other I gasped. (really)