Green’s Dictionary of Slang

1. to become run-down, slovenly.

1876

J. Greenwood Low-Life Deeps 51: If she hadn’t been a real lady bred, sir [...] she’d have gone ‘slommicking’ as we say.

2. to move in a slovenly manner; thus slummocking adj.

1879		‘’Arry on ’igh Art’ in Punch 1 Feb. 42/2: A fig for your Classical attitoods, wobbles, and slommocking walks!
c.1905		J. Furphy Buln-Buln and the Brolga (1948) Ch. i: 🌐 Shed your duds, you slummockin’ beggar!
1928		V. Palmer Passage 102: When the Wiegerts were working for themselves, they were inclined to slummock along.
1950		C. Harris Three-Ha’Pence to the Angel 95: She sniffed [...] and slummocked into the scullery.
1963		A. Baron Lowlife (2001) 184: She turned away and slummocked downstairs without looking back.

3. to clean carelessly or half-heartedly.

1923

J. Manchon Le Slang.