"condom," by 1939, slang, from scum + bag (n.). Earlier (by 1817) it was used in sugar refining as the name of a frame covered in coarse cloth used in straining. Meaning "despicable person" is attested by 1971.
(also scumbucket or scummer or scumsack or scumster or scumwad) A despicable person; asshole, bastard, sleazebag: calls Charlton Heston a scumbag/ Everybody says he was a scumbucket/ The scummers were dressed sleeveless now/ And another opportunistic scumsack limps straight to a lawyer
[1960s+; fr scum, ''semen'']
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source