Scum is a word used to describe something gross, worthless and difficult to get rid of. The term "scum" can be used to refer to a wide variety of different things, including literal messes, as well as human beings and fictional characters. Using this term to refer to human beings is considered insulting. Liberals tend not to use words like scum because liberals think human equality is important. Despite this in cases like criminal Nazis, the KKK and those responsible for the Priest child molestation scandal even liberals are tempted to call them scum.