When they thought about Lewis, what struck the players most was that he never acted like a do-gooder.
Kosove says the role of “some Southern Christian Bible-thumping do-gooder” read like a caricature to her.
To hear her speak is to hear that passion combined with the heart of a do-gooder and the simplicity of a child.
"a person who seeks to correct social ills in an idealistic, but usually impractical or superficial, way," 1650s (as do-good), in "Zootomia, or Observations on the Present Manners of the English: Briefly Anatomizing the Living by the Dead. With An Usefull Detection of the Mountebanks of Both Sexes," written by Richard Whitlock, a medical doctor. Probably used even then with a taint of impractical idealism. Modern pejorative use seems to have begun on the socialist left, mocking those who were unwilling to take a hard line. OED has this citation, from "The Nation" in 1923:
There is nothing the matter with the United States except ... the parlor socialists, up-lifters, and do-goods.The form do-gooder appears in American English from 1927, presumably because do-good was no longer felt as sufficiently noun-like. A slightly older word for this was goo-goo.
A person whose selfless work may be more pretentiously than actually altruistic; an ostentatiously right-minded citizen: a professional dogooder (1927+)