no slouch, n. — Green’s Dictionary of Slang

no slouch n.

something or someone good, acceptable, enterprising, energetic.

1754		T. Sheridan in Brave Irishman in Coll. Most Esteemed Farces (1792) 202: Fait, my jewel, I don’t know a more peaceable companion than sweetlips here (putting his hand to his sword); but if he’s provoked he’s no slouch at it.
1767		‘Andrew Barton’ Disappointment III i: He’s no slouch of a fellow!
1770		‘Poetical Essays’ in Oxford Mag. V–VI 234/1: My cousin’s no slouch at your reading and writing, / Tho’ now for his play, he’s as pale as a whiting.
[1800		G. Colman Yngr Heir at Law III ii: This is all the go, they say! [...] Slouch is the word, now, you know].
1819		H.H. Brackenridge Modern Chivalry 56: I perceive, Captain, said the Principal, that you are no slouch at supporting a paradox.
1833		Spirit of the Times (NY) 12 Jan. 1/2: ‘This gentleman is considered the best shot in the county’ [...] and the result shows that he is no ‘slouch’.
1840		C.F. Hoffman Greyslaer II 187: Why, Kit Lansingh, my boy, you are no slouch of a woodsman to carry a yearling of such a heft as that .
1866		Border Watch (Mt Gambier, SA) 31 Oct. 3/2: THE LATEST SLANG CREATION IN NEW YORK [...] His friends are ‘gay ducks,’ ‘no slouches’ ‘bullydogs’.
1872		‘Mark Twain’ Innocents at Home 334: He was always nifty himself, and so you can bet his funeral ain’t going to be no slouch.
1898		(con. 1875) F.T. Bullen Cruise of the ‘Cachalot’ 107: He was no ‘slouch’ at the business either.
1902		A. MacGowan Last Word 6: I guess you’ll agree my job was no slouch, neither.
1912		Bookman VIII 126: But, I see, the Kaiser is no slouch either.
1942		J.S. Redding No Day of Triumph 187: He had my old man by some percentage on lying, an’ my old man wasn’t no slouch.
1955		Mad mag. Aug.–Sept. 25: G.G.W. was no slouch with the women.
1960		C. Cooper Jr Scene (1996) 280: Patterson was no slouch in the guts department.
1975		E. Torres Carlito’s Way 60: Nacho’s boys was no slouches, either.
1990		F. Koger Countdown! 166: The Colonel was no slouch; he had won three or four games with good players.
2004		A. Fine ‘The Cat Who Knew How to Live’ Chicken Soup for the Soul Celebrates Cats 2: Cookie was no slouch, and there wasn’t a self-respecting mouse that would dare cross his path.