As I watched volunteers cleaning the unfortunate animal victims of the oil spill in the Gulf of Mexico, I thought, "What a great thing to do... but why stop there? Aren't all animals stinky and gross?" A walk in the rain or a river crossing is the closest most of them ever get to taking a bath, and those activities so rarely involve soap that I'm not even sure they count.
Monkeys get clean by picking bugs out of each other's back hair... and then they eat the bugs they find. That's a little bit like taking a bath except, where a bath makes you clean, this just makes you disgusting. Other animals, such as lions, clean their young by licking them. In that way, a lion's tongue is like a wash cloth... a wash cloth that was just used to clean out a zebra's carcass.
So don't think you have to go all the way to the Gulf of Mexico to clean animals. Grab a brush and some shampoo and start tidying up the animals where you live. The ones that don't kill you will be slightly less gross because of the service you provide.