Truth and Lies

Truth: Noun. That which most easily appeals to the fears, hopes, and prejudices of the hearer; in essence, a lie.
Lie: Noun. That which causes its utterer to be reviled; in essence, the truth.
Deceit: Noun. Example: A dog rolls on the carcass of a dead possum in order to deceive other animals regarding his identity as a dog (whereas) a man lolls in the scents of church in order to deceive himself regarding his identity as a thief, an adulterer, and a liar (the difference is that the dog does not first have to endure being bored by the possum).
Thorax, 9 Chickweed Lane

Truth, lies, and deception. If only it were easier to tell them apart. Listed are multiple tropes that fall into one of the three categories. And The Shades of Fact offers insight into their fictional equivalents.

Tropes of Truth

First, recognize honest intent, whether expressed as the plain truth or a technical falsehood.
See also A Trusting Index and the Information Desk.

Tropes of Deception

Second, learn the myriad shades of deception, purely for self-defense, of course.
See also Espionage Tropes and the Infauxmation Desk.

Tropes of Lies

For outright fabrications that may never be discovered as such.
See also Dirty Social Tricks.