Green’s Dictionary of Slang

(US gay) an ageing, unattractive male homosexual.

1972		B. Rodgers Queens’ Vernacular 132: Mary Worthless (camp) very old queen one might encounter at the gay saunas; a meddlesome old fool.
1979		Maledicta III:2 222: Cinderella becomes Old Ella, the whining failure or whoring harridan, derisively [...] subjected to digs about antiques, puns on famous names (Mary Worthless, from the US comic strip).