Twice this summer I have seen people who have no business being face painters. Both were using acryic paint and neither had proper sanitation. Acrylic is "non toxic" but that's not the same as "safe for skin" I've met over a dozen people who have had children with very bad reactions to acrylic craft paint used as face paint. Also only cosmetic glitter should be used, not craft glitter or glue.
although the friend who commented probably won't mind if I left her name visible, but I have not checked with her, so I blurred it out.
One of the two I saw recently took it a step further than just bad paint and no sanitation. She let her own kids run wild through other people's booths, let the baby eat discarded food off the asphalt and breastfed while painting someone's face. I'm as militant a person as you'll ever meet about a woman's right to nurse in public. I did with all 4 of my kids, but there is a time and place and while you are actually working is not. Especially if you are supposed to be interacting with someone else's child.
But so many people get it right and they are not hard to find.
Click this link to a gallery of an excellent face painter in Chicago. She only uses quality FACE PAINT and has fantastic sanitation and safety standards. http://theclassyclown.com/FACE%20PAINTING/FacePainting1.htm
There are several good ones here in Kansas City. Sister Act for example.
If you're thinking of starting out in facepainting, check out this article and then google many others to get an idea of what you should and should not be doing.
Need supplies? There are tons of places, but Mirae is a good place to start. She's been doing this for awhile and knows her stuff.