Green’s Dictionary of Slang

a ‘white-collar’ criminal, e.g. confidence trickster, embezzler.

1986		J. Ellroy Suicide Hill 227: [of an embezzler] ‘I staked out Hawley for days, watching him glom them greenbacks [...] I’m thinkin’, “Too bad there's only one of these scamsters”’.
1998		N. Kazmi Dream Merchants of Bollywood 174: A scamster, guilty of robbing crores from the national exchequer.
2000		J. Ellroy ‘The Trouble I Cause’ in Destination: Morgue! (2004) 187: I skirted scurfy scamsters and chirpy child molesters.
2003		D. Swierczynski Complete Idiot’s Guide to Frauds, Scams, and Cons 172: The scamster then had three accomplices create forgeries of the deeds.
2021		J. Ellroy Widespread Panic 17: Scores of scurrilous scamsters licked up my largesse.

a confidence trickster.

1978		L.K. Truscott IV Dress Gray (1979) 428: The notorious Billy Dickey, the well-bred dude scam artist.
1989		A. Vachss Hard Candy (1990) 98: She was a high-style scam artist who hated the freaks.
1993		G. Disher Deathdeal [ebook] ‘We’ve had word that a ring of scam artists is in town’.
1996		V.M. Knight Florida Scams 123: The scam artist knows all about the victim’s loss, since he, or she [...] probably played a role in bringing that loss about.
2009		K. Farmer Stealing You Blind 7: The con man or scam artist can be male or female, young or old, and can be of any race.
2013		T. Dorsey Riptide Ultra-Glide 224: Just like that ballroom scam artist told us.

a trickster, anyone who can get ‘something for nothing’, someone who is cunning but not necessarily criminal.

2004

posting at alt.religion.scientology 15 Apr. 🌐 Wasn’t it, that I read about you or even from you about you doing the porter at, was it Flag, seeing the old scamhead driving in a big car.

(US) the ensnaring of a client by a girl, often a prostitute, and his subsequent robbery, either by the woman herself or, more often, by her pimp, posing as an ‘outraged boyfriend’, who emerges, while the pair are in flagrante, from a hidden door or panel in the bedroom wall.

1980

Garrison Snakedoctor 59: They’ve been working the old crocodile scam [...] They get some joker in the motel room [...] then the husband or boyfriend shows [HDAS].

(US) what’s happening? what’s going on?

1971		E.E. Landy Underground Dict. (1972).
1993		Watchmen ‘Try It Sometime’ 🎵 on McLaren Furnace Room [album] Hey man what’s the scam [...] Hey Jon what’s going on? [...] Hey Sam what’s the plan.