Green’s Dictionary of Slang

sales lady n.

[as in salesman n. (2)]

(US) a prostitute.

[US] ‘Jargon of the Und.’ in DN V 461: Saleslady, A prostitute.
[US]Ragen & Finston World’s Toughest Prison 816: sales-lady – A prostitute.
[US]B. Rodgers Queens’ Vernacular.