Definition & Meaning of "shit sniffer"in English

What is the origin of the term "shit sniffer" and how is it used?

"Shit sniffer" is a vulgar slang term used to describe a person regarded as disgusting, repulsive, or unpleasant. It likely developed in English in the 20th century as a literal and crude metaphor, combining "shit" (feces, symbolizing filth) with "sniffer" to imply intimate contact with something foul. The term is informal, highly derogatory, and used in hostile, mocking, or aggressive contexts to insult someone's character, habits, or personality. It is never neutral and is intended to provoke disgust or contempt.