Don't let your brush touch those shoes until you've stripped the shit off. Damp cloth, rub rub rub, dry off. Do that until your cloth stops coming off filthy. My C&J shells are more porous than Alden (even though they're all Horween), so don't be surprised if the Reno discolors the shell. They will eventually return to normal.
I can't overstate how much shit those shoes have on them from the factory.