Everyone has lied. That Kevin thinks he exposed a time when he lied in his life doesn't mean he's a liar. Throwing the word around that loosely obviously ruins any meaning it might have.
Stem, John Taylor was confronted on the issue of polygamy. He planned his response very carefully and on that issue he said it was an outrageous thing, and then he went on to read D&C passages that command men to be husbands to only one wife. At this time Taylor was married to multiple women, as were numerous LDS officials at the time.
So he was, to say the least, intentionally deceiving his audience. He wanted to assure them that Caswall's claim had no credibility. But he knew if he conceded the point on polygamy, that his smear campaign against Caswall would fail miserably, as it would prove he was credible on at least some things. Taylor couldn't afford him to be credible on any thing.
He later went on to make up things about the Haven interview, inserting comments she never said.
These are two ironclad examples from this one event of a conscious effort to deceive an audience. These weren't "mistakes" or goofs. These were egregious lies.
Now if Taylor cannot be called a liar, then who can be?
Keep in mind that anti-Mormons are called liars on a regular basis by your buddies over at MAD. Hell, Pahoran called me a liar no less than three times last week and I never once reciprocated.
Funny how there was no uproar over at MAD about how Pahoran had "ruined his own credibility" for calling me a liar. The mods sat by and watched, and did nothing. Well, they banned me, but that was about it. In that last thread Pahoran said my bigotry surpasses that of those who murdered Joseph Smith. So, I'm worse than a murderer, and I am regularly called a liar.
Of course there was never any evidence that I had lied about anything, and I even asked Pahoran to explain what his evidence was for whatever it was I supposedly lied about. He just dismissed the CFR and moved on to some other variant of the "liar" slur.