The laws of haircolouring

There are three laws, and they go hand in hand with the stuff you learnt about robotics, motion and thermodynamics. The first two are whatever you want them to be. So, for example, you may choose to have:

1. Blondes have more fun (and gentlemen prefer them too)!
2. Change is good!

But they must always always give precedence to the third rule:
3. If it ain’t broke, don’t fix it.

Otherwise you run the twin risks of Nelly Furtado and Robert Downey, Jr.