Sorry to be a bit.. basic, but this is a serious point.
I have played a bit of village cricket in my time, and seen the rejuvenating effect that a regular application of earwax ('EW' for the faint-hearted) can have on leather. It's almost miraculous. Someone should market it as an expensive dressing for Audrey Hepburn's kid evening gloves..
Scarifying the unpolished side of a ball with earth from your pocket is famously considered 'tampering'. So polishing the shiny side with 'EW' should also be illegal.
But then, it is a natural product, like spit, which is routinely used in at Test level. And cricket is nothing if not a game of natural products - willow, leather, ash, flannel, cork, grass, chalk - it's practically an eco-system unto itself.