Green’s Dictionary of Slang

1. (US) a vociferous, but non-participating critic.

1889

World (N.Y.) 26 Oct. 7/2: Corkhill then drove the ball to left for a base, and Visner scored the first run for Brooklyn. How the Brooklyn hamfatters did howl.

2. (US, also hamfatto) an ineffective actor or performer, a mediocre jazz musician; a second-rate boxer.

1882		G.A. Sala America Revisited I 66: Every American who does not wish to be thought ‘small potatoes’ or a ‘ham-fatter’ or a ‘corner loafer’ is carefully ‘barbed’.
1883		Nat. Police Gaz. (NY) 22 Dec. 3/2: Mike Rentz is willing to bet [...] that no ‘hamfatters’ or ‘chairwarmers’ (his polite titles for the ‘profession’) will dare organize any meeting to denounce him.
1889		Daily Morn. Astorian (OR) 16 Mar. 3/1: It is not an uncommon thing for a group of traveling hamfatters or a dizzy group of barn stormers to beat a poor newspaper man out of money.
1897		Eve. Bulletin (Maysville, KY) 12 Nov. 4/3: I started out in tragedy, but it’s played out. Such hamfatters as Booth [...] and men of that ilk have ruined that line of business.
1906		S. Ford Shorty McCabe 129: He [...] got away with his bale of hay as regular as a Rialto hamfatter raidin’ the free lunch.
1911		G. Mager ‘Sherlocko the Monk’ [comic strip] Observe, Watso, that Hamfatto has the leading role to-night!
1911		S. Ford Torchy 60: And to think of a hamfatter like McCallum [...] havin’ the nerve to call himself a school of dramatic art!
1914		E. Wittmann ‘Clipped Words’ in DN IV:ii 122: ham, from hamfatter. A third-rate actor.
1919		Wash. Times 16 Feb. 19/7: Another hamfatter, Tom McMahon, defeated him in twelve rounds.
1948		Mencken Amer. Lang. Supplement II 689/2: The Lexicon of Trade Argot prefers to derive it from the fact that actors formerly used ham-fat instead of cold cream to remove their make-up, and this is supported by a variant form, ham-fatter.
1999		Indep. on Sun. 17 Oct. 30: A ‘hamfatter’ in 1880s America is said to have been an unsuccessful actor.

3. (US Und.) a second-rate confidence trickster.

1928

(con. 1900s) J. Callahan Man’s Grim Justice 25: Dese mugs from Boston and Phila and Cheecargo ain’t grifters [...] dey’re just eighteen-carat ham-fatters, finks, ‘heads-I-win-and-tails-you-lose’ guys.