After thinking about it, I think what spock meant in the 'Courtmarshel' was that Vulcans were incapable of fooling the computers by lying, whether that is true or not. But I'd like to see Vulcans actually be literally incapable of lying. I think that would be more interesting but which was negated in 'Enterprise' and not just have a reputation for truthfulness. I'd like to see a poll.