I have never washed an egg in my life, whether for eating or hatching. If it has a LOT of poop on it, I have a little bucket of play sand I keep handy to scrub it off in the sand. I do not want to wet an egg and let all the stuff on the outside soak into the inside. Eggs are porous and absorb things. Nothing like wetting a poopy egg and letting it absorb some of that mess.