I had never come across that word before, so I just looked it up on the internet.
The first reference to it I found was the Merriam-Webster Dictionary which defines it as 'an awkward, uncouth or slovernly person'.
Then I discovered the word had been used by our own Australian feminist, Germain Greer, in a piece about gender roles in house-cleaning in her book The Whole Woman.
She says that a man who is slovenly and untidy is considered normal; the woman who is, either a slut or a slommack or a slovern or a slag. [Source: Daily Times, Pakistan, 27 January 2010]
I can see why Jimmy reported the woman at the show to the police, and had her make a public apology to Ethel in the local newspaper.
The website Legends of America.com suggests 'slommack' is a word from the Old West meaning 'prostitute, floozie, slut or dirty untidy woman'.
There were American miners at the Gulgong goldfields and they may have introduced the word into the local vernacular.
Internet Archive (www.archive.org) reveals that the word 'slommack' was part of the south-east Worcestershire dialect in England in the 1890s as a verb meaning 'to shuffle along in an idle ungainly manner'. Another reference on that website suggests it was also one of the dialectic words of the counties of Northampton and Leicester.