Red herring

[6][7][8] For example, the character of Bishop Aringarosa in Dan Brown's The Da Vinci Code is presented for most of the novel as if he is at the centre of the church's conspiracies, but is later revealed to have been innocently duped by the true antagonist of the story.

[10] When I was a boy, we used [to], in order to draw off the harriers from the trail of a hare that we had set down as our own private property, get to her haunt[11] early in the morning, and drag a red-herring, tied to a string, four or five miles over hedges and ditches, across fields and through coppices,[a] till we got to a point, whence we were pretty sure the hunters would not return to the spot where they had [been] thrown off; and, though I would, by no means, be understood, as comparing the editors and proprietors of the London daily press to animals half so sagacious and so faithful as hounds, I cannot help thinking, that, in the case to which we are referring, they must have been misled, at first, by some political deceiver.

A variation of this story is given, without mention of its use in training, in The Macmillan Book of Proverbs, Maxims, and Famous Phrases (1976), with the earliest use cited being from W. F. Butler's Life of Napier, published in 1849.

[19] According to a pair of articles by Professor Gerald Cohen and Robert Scott Ross published in Comments on Etymology (2008), supported by etymologist Michael Quinion and accepted by the Oxford English Dictionary, the idiom did not originate from a hunting practice.

Cobbett recounted that he had once used a red herring to deflect hounds in pursuit of a hare, adding "It was a mere transitory effect of the political red-herring; for, on the Saturday, the scent became as cold as a stone.

"[13] Quinion concludes: "This story, and [Cobbett's] extended repetition of it in 1833, was enough to get the figurative sense of red herring into the minds of his readers, unfortunately also with the false idea that it came from some real practice of huntsmen.

"[20] The Oxford English Dictionary makes no connection with Nashe's quote and the figurative meaning of red herring to distract from the intended target, only in the literal sense of a hunting practice to draw dogs toward a scent.

[21] Although the hound used in the test stopped to eat the fish and lost the fugitive's scent temporarily, it eventually backtracked and located the target, resulting in the myth being classified by the show as "Busted".

In the mystery novel A Study in Scarlet , the detective Sherlock Holmes examines a clue which is later revealed to be intentionally misleading.
Herrings " kippered " by smoking, salting and artificially dyeing until made reddish-brown, i.e., a "red herring". Prior to refrigeration, kipper was known for being strongly pungent . In 1807, William Cobbett wrote how he as a child together with other children used a kipper to lead hunting dogs away from the scent of a hare the children intended to hunt—an apocryphal story that was probably the origin of the idiom.