ichidan verb, intransitive verb
get slightly dirty; become a little soiled
Describes something becoming lightly dirty all over, often through gradual use or exposure. Intransitive.
白いシャツがうっすらと薄汚れてきた。
The white shirt has gotten slightly dirty.
長年使ったカーテンが薄汚れている。
The curtains, used for many years, are lightly soiled.