smell test
n. A metaphoric test used to determine the legitimacy or authenticity of a situation.
WBBM-Ch. 2 fired long-standing medical reporter Dr. Michael Breen on Tuesday, claiming he had violated journalistic standards by using similar voiceovers in reports aired in May and October, according to Breen.

Breen, who has been with the station since 1995, said he plans to sue over what he labeled an unfair attempt to avoid paying him the remaining three years of a four-year contract. "They said I was recycling material and that was grounds for dismissal," Breen said. "They're trying to save themselves money at the cost of my reputation. We'll see if this passes the smell test with the people of Chicago or with a judge."
—Steve Johnson, “Channel 2 faces lawsuit after it fires reporter,” Chicago Tribune, November 13, 2002
1975 (earliest)
Most firms say their use of private investigators is strictly limited. Robert J. Boutillier, partner in charge of U.S. operations at Peat, Marwick, Mitchell & Co., the largest accounting firm, says an agency would be used only if a prospective client did not check out well in the course of the usual inquiries to lawyers, bankers, investment bankers, and credit associations. "It has to pass the smell test," he says of a new client. "If there's a problem that requires looking into, we might use investigators. Or we might not want to bother with it."
—“When accountants hire private detectives,” Business Week, June 30, 1975
This fragrant phrase comes from the idea of smelling food in advance as a test to see if it has gone bad.