足が汚れているよ。

foot; leg; gait; pace; bottom structural component (i.e. radical) of a kanji; means of transportation; money; coin

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to get dirty; to become dirty; to become sullied; to become corrupted; to lose one's chastity

indicates certainty, emphasis, contempt, request, etc.; used when calling out to someone; used to catch one's breath or get someone's attention; yo!