Sometimes I hear or read people's comments about how they would never own a grey because of the trouble keeping them clean. Poppy is my first grey and I really don't use too many additional tricks to grooming that I don't use with my other horses.
GROOMING AT HOME
Get used to dirt and Poopy stains. Period. I do not believe in over bathing so my horses do not get a full on soapy bath at home often. Instead I curry (and curry, and curry) and brush daily. This gives them a lovely shine. Manes get brushed but never the tail.
HORSE SHOW GROOMING
I use Ivory soap to bathe. Not the knock off store brand, but actual Ivory. When I do the legs I squirt some in my hand and hand scrub them. I also dip her tail in the bucket and scrub her tail between my hands. Her mane is pretty grey but her tail has some golden coloring so I will take some Quicksilver and scrub to get out any yellowing. Leave it on for a few minutes. You can also do this for the legs if they are REALLY dirty but 90% of the time, the Ivory does the trick. Only after the bath do I spray Show Sheen (or whatever tail conditioner you choose) on the tail. When dry THEN you brush. Dry legs and body with a towel.
Grey horses love to sleep in their poop. It is inevitable that when you arrive at the show they will greet you from their stall with giant poop stains. Here are poop stain removing tricks I use:
* dab rubbing alcohol on a cloth and rub onto stain. You can also put rubbing alcohol in a spray bottle and spray stain if it is large. Then scrub with cloth.
* wet cloth (or sponge), put a drop of ivory on it and a rub stain.
To remove dust particles (especially after gorging oneself with hay) or to give a shine I like to use Alpha Keri.
I fill about a 1/4 of a spray bottle with Alpha Keri then the rest with water. Shake well and either spray body or spray onto a cloth. It will bring dirt to the surface and you can wipe the coat clean.
It also helps at the shows to keep the stall regularly picked clean to keep staining arsenal to a minimum.