In "The Menagerie" McCoy says to Kirk that "Spock is a Vulcan so he is incapable of lying.", while they are on Starbase 11, just before McCoy is called back to the Enterprise to address a medical situation.
True, but Kirk counters that he's also half-human, thus allowing for the possibility of his lying.
To which McCoy responds "That half is so buried that to be caught acting like us would be embarrassing to Spock." or something similar to that, thus not allowing for the possibility of Spock lying.
Navigator NCC-2120 USS Entente
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But Spock was LYING all through
The Managerie; from the point where he was cross circuting the Starbase computer to send all those faked messages concerning a secret mission, to recalling McCoy to the Enterprise; to telling the Bridge crew Kirk had been assigned 'rest leave' on the Starbase, to the fake court martial proceeding with the illusion of Commadore Menendez (rememebr Spock tells Kirk at the end of the episode that the whole court martial proceeding was a ploy cooked up between himself and 'The Keeper' to prevent Kirk from trying to take back control of the ship before it reached Talos IV).
So, honestly, I don't get the idea that ANY fan who watched all 79 (80 after 1991) episodes believed that Spock (or other Vulcans were incapable of lying).
Hell, you want to see an example of a full blooded Vulcan lying his butt off, look no farther than Spock's father, Sarek, in
Journey to Babel - he was lying to Amanda during trhe entiire trip; and lied to Kirk directly in a vain attempt to keep his heart condition a secret from EVERYONE.
Then, as pthers brought up, there's T'Pring and Stonn and the whol;e
Amok Time situation.
Then there's
Errand of Mercy; where Sopock tries to pass himself off as a Vulcan merchant - and furthermore, IF Vulcans were totally incapable of lying, I woiuld SURE AS HELL not want them serving anywhere in StarFleet during a war or any armed conflict as, were they to be captured, they'd answer every question asked of them by an enemy truthfully.
So, again, if you watched the series - I don't see how amyone can not realize that when Spock says tp the Romulan Commander, re the myth that Vulcans are incapable of lying, and he replies, "It is not myth..."; he's lying his a$$ off; and further; all Vulcans (full-bloded and half-blooded, makes no difference) are FULLY capable of lying when it serves a logical purpose.