粪土

粪土 is almost always used figuratively in the set frame 视...如粪土 ('regard ... as dung'), to describe someone who scorns wealth, fame, or worldly things. Mao Zedong's famous line 粪土当年万户侯 ('treated the high lords of yesteryear as dung') made this phrasing iconic.

Literary and emphatic. In ordinary speech, you wouldn't call something 粪土 — you'd say 不值钱 (worthless). Reserve 粪土 for declarations of contempt.