rotter, dirty dog, rat, skunk, stinker, stinkpot, bum, puke, crumb, lowlife, scum bag, so-and-so, git -- (a person who is deemed to be despicable or contemptible; "only a rotter would do that"; "kill the rat"; "throw the bum out"; "you cowardly little pukes!"; "the British call a contemptible person a `git'")
tramp, hobo, bum -- (a disreputable vagrant; "a homeless tramp"; "he tried to help the really down-and-out bums")