At my stable most of us use 'Glo White'. :)
It's pretty much purple goo that makes all white horsies really
clean and well, white. :P
But if you don't rub it in properly/wash it out properly, it tends to leave the horses looking purple. Which is really lame if you have a show to go to, but hilarious if it just a normal day.
My 'ex'-friend used to use that coloured hairspray (know that stuff? They use it at like school carnivals and like shows and stuff) on her white ponies many and tail to make him look like a My Little Pony.
It used to make his hair horrible and dry, if she didn't wash it out it would start falling out.
So do not use that! >-<
Have a good one.