Strongly disagree, though I'm not completely certain: people use all their powers of rational thinking to convince themselves (if nobody else) that what they're

Strongly disagree, though I'm not completely certain: people use all their powers of rational thinking to convince themselves (if nobody else) that what they're doing is quite alright. So if you spot somebody lying, chances are it will show up in their reasoning if you question them about it at length—and they'll tell you about it, directly, because they've convinced themselves they're right. I think that's one way to explain why you should believe things people say about their own beliefs in interviews (while being skeptical about whether it's actually right).