Spending hard earned money on a great rope is a bit of a waste if you then subject it to dirt and grime at the crag - not only does it add to the dirt left on the belayers hands, but it reduces the lifespan of your rope significantly.

On the subject of dirty hands, did you know that the dark residue left on your hands (especially lowering a climber / abseiling) is often aluminium from the carabiners / devices in friction against the rope - and you can clean your rope with Nikwax!