Unfortunately black is very hard to keep clean.
I'm finding that with my new Scoobie - the green one looked fine when plastered in mud and the contents of our local lanes - just a bit rural/agricultural/working vehicle.
The black one (green no longer available) however just looks naff and unloved with even a light undercoat of dirt, and really minging by the time the bird poo and tree sap have added a top coat.