Green’s Dictionary of Slang

(Aus./US) low, common, vulgar.

1852		A. Harris (con. 1920s) Settlers and Convicts 11: The poor Australian settler (or, according to colonist phraseology, the Dungaree-settler, so called from their frequently clothing themselves [...] that blue indian manufacture of cotton known as Dungaree).
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
1957		‘Weldon Hill’ Onionhead (1958) 303: This ship is [...] some kind of proud symbol, a dungaree Navy vessel that killed a submarine.
1986		(ref. to mid-19C) R. Beckett Dinkum Aussie Dict. 23: Dungaree settler: Archaic. An early member of the now international blue jeans set who settled in the Hawkesbury River area of the infant colony of New South Wales. Most were poor and the survivors quickly became inbred. In short, a term of derision similar to the Americanism ‘cracker white’.