speck — a small spot differing in color or substance from that of the surface or material upon which it appears or lies: Specks of soot on the window sill.
unpolluted — made unclean or impure; contaminated; tainted: swimming in polluted waters.
unspotted — having no spots or stains; without spots; spotless: an unspotted breed of dog; unspotted trousers.