scummy

adjective, scum·mi·er, scum·mi·est.

1. consisting of or having scum.
2. Informal. despicable; contemptible: That was a scummy trick.

adjective -mier or -miest

1. of, resembling, consisting of, or covered with scum
2. dirty, unpleasant, or nasty

adj.1570s, from scum + -y (2). Transferred sense of “filthy, disreputable” is recorded from 1932. Related: Scumminess.