A blackboard seems to fit.
The best way to get dirty socks white is to bleach them in warm water. You can also use stain removing products and wash them.
Ridin Dirty
It's a penguin rolling down the hill.
Ridin dirty
A white girl acting black
Blackboard
A chalkboard is black when clean and dirty when written on with white chalk.
The answer to the riddle "What is black when it's clean and white when it's dirty?" is a chalkboard. When a chalkboard is clean, it appears black; however, when you write on it with white chalk, it becomes "dirty" and takes on a white appearance.
A blackboard
Blackboard
A blackboard.
A chalkboard ~_~
A chalkboard ~_~
A chalkboard ~_~
Black will look the cleanest, white will be the easiest to tell when its dirty, but all 3 are about the same in degree of difficulty to clean which it is fairly easy to clean a microwave.
A black car.A black dog.Black clothes.A Panther.
ChalkBoard(reason:when chalk is on it,which is dirty,it is bright because it is white,when it is clean which nothing is on it it is dark green.)