I'm a huge fan of a product called Smart Choice by Cut Heal. I love the way it cleans my horses without being sticky or slippery. The only thing I can't vouch for is how well it cleans a light colored horse, as all my beasties are bay and chestnut. It seems to do a pretty good job on their markings, but none of my crew have much chrome to speak of either!
~ A true friend knows all there is to know about you and still likes you. -E. Hubbard
Arrowroot powder :~) I have a very light appy (cream with buckskin colored spots) and it works pretty great. Leaves him soft and pretty darn clean (he's a poop pile roller). Sprinkle it on, massage it in and brush out.
I spray witchhazel on soiled spots and they scrub right out.