Bullshit Detector was the name of a series of compilation LPs put together by the punk band Crass and released on their Crass Records label. Three editions were released between 1980 and 1984, consisting of demo tapes, rough recordings and artwork that had been sent to the band. The sound quality of the Bullshit Detector series was mixed, and was often very basic or poor as Crass would master the tapes directly to record without any additional production or enhancement. For Crass, the expectation of a polished performance was missing the point of the DIY punk ethic:

"Don't expect music when the melody is anger, when the message sings defiance, three chords are frustration when the words are from the heart"

- Sleeve notes from Bullshit Detector Volume 3

The title Bullshit Detector was derived as a reference to the Clash song "Garageland" from their first LP The Clash. That reference, in turn, may be taken from a quotation attributed to Ernest Hemingway: "The most essential gift for a good writer is a built-in, shock-proof, bullshit detector."

A fourth Bullshit Detector, this time an international compilation, was released by the Swiss independent anarcho-punk record label Resistance Productions in 1994.

See also: Cassette culture