Green’s Dictionary of Slang

one who leaves without paying off their debts or bills.

1866		Bombay Gaz. 4 Sept. 3/4: [A] fellow who flees from his creditors [...] they call him a ‘sloper’.
1896		Bulletin (Sydney) 18 Jan. 3/2: You strike the stores for credit. They’ve all ‘heard that yarn before’ / They’ve ‘had enough of slopers’, an’ they ‘don’t take any more!’.
1898		H.H. Lewis A Gunner Aboard the ‘Yankee’ 59: The man [...] was looked upon as a ‘sloper,’ or one who ran away from work.
1906		Sun. Times (Perth) 16 Sept. 4/8: The venemous are certain by the ‘Sloper’ he’s skedaddled.
1908		Sun. Times (Perth) 31 May 1/1: The sloper is the principal curse of the country [...] after taking down battling widows and others these human vermin depart to other dupes.
1915		A. Wright Sport from Hollowlog Flat 108: As is always the case on large camps, there was a number of ‘slopers’, men who collected their wages and left their creditors to mourn their loss [AND].
1981		H.C. Mills No Regrets 78: The ‘sloper’ – the man who decamped without paying his debts, the worst of criminals [AND].