Oh, that is SO me!! The visions I had in my little pea brain. Painted the inside of my coop white. It was so bright and cheerful and I was going to have Coca Cola chickens. You know, I'd like to teach the world to sing in perfect harmony? Yeah, they didn't learn that song, and I don't have the lap chickens I thought I'd have. Then they moved into their flawless coop. You know, it's kinda like owning nice house and renting it out to teenagers as their first "adult experience." Sounds great, but reality is ugly. So is my white coop! I have yet to figure out how chickens can get chicken poop spattered on the wall above the window, which is above the roosts, which are above the nests, which are above the floor. <sigh>
But you know what? The chickens don't care. And after a few months I didn't care anymore either. They were healthy, they did chickeny things and now I have a lovely coop with a gray/brown interior. I just pretend I painted it that way.
I use deep litter, and that can get pretty dusty in the summer too. If you wait long enough, the whole coop will be the same color again.