Why is the paint, missing on the characters in Toy Story 3 ?

I'm talking about the scene, when Buzz and the gang get the paint all over their bodies from the messy toddlers who were throwing them around, and spitting and drooling all over them at Sunnyside.

After that happens, the paint is still on them but later on in the movie it disappears as if it was never there, even though they never washed it off.