A Micabella Girl is a girl who works at the makeup store, counter, or kiosk Micabella. She is known for having outlandish makeup, Micabella of course, that only a prostitute or whore would dare apply. It is not necessarily the cheap makeup that Micabella sells that makes it look so bad, rather in the way it's painted on by the scandalous skanks who think they are makeup artists.
An example of a Micabella Girl would be a wannabe MAC (cosmetics) girl, only they don't know how to apply makeup. They most often use shades 3/4 of their eye lid that ranges from the colors of Charcoal Gray to Charcoal Black. The rest of the lid, below the eyebrow, is slathered on by about 5 coats or more of the base primer, which is normally used under eye shadow, for "definition".