scum

n. 浮渣,水金秀,槽粕
v. 将浮渣去除掉,产生浮渣

I wouldn't have anything to do with those scum.

我不会和那些无耻之徒来往。

When the meat is boiling, remove the scum.

当肉煮沸时，把浮在上面的浮渣撇掉。