The candidates started 'slinging mud' (at each other) early in the campaign.
His shoes were covered with 'mud'. = His shoes were caked in/with 'mud'.
The scandal ruined his reputation and now 'his name is mud'.
(..) it wouldn't be called the wild, would it? -The wild? -Whoa. Hold up there a second, fuzzbucket. You mean, like, the "live in a mud hut, wipe yourself with a leaf" type wild? -Who wipes? -Oy vey. -Oy vey! -Oy vey, everybody! (..)2005 Madagascar