# red herring something intended to divert attention from the real problem or matter at hand; a misleading clue. Red herring is herring that has been cured by smoke, a process that changes the color of the flesh to a reddish hue. Its persistent odor is very useful, if trailed over the ground, for training a dog to follow a scent. But a dog which gets a good whiff of red herring will lose any other scent that it has been following. Criminals who have been chased by bloodhounds have used this knowledge to advantage. Thus the expression to drag a red herring over the trail and similar expressions are used to refer to anything which misleads one or causes one to lose the trail.