Which celebrity beauty brands are really successful?

In the 1400s, God sent clouds of locusts, swarms of frogs and a litany of lice to punish the humans in what is now known as The Plagues of Egypt. In the 21st century, we've had our own fair share of plagues. The first was the celebrity fragrance. You might remember Beyoncé's Heat, Sarah Jessica Parker's Lovely, Britney Spears' Fantasy - or any of their twenty individual incarnations, which formed an inescapably sweet scent that clouded every Boots and Superdrug.

Then came the apps. "The Jeremy Renner app is a must have," Jeremy Renner probably said. Then came the subscription ...