@futurebird ...I think one thing that blunts the distinction, and makes skepticism too easy to game, is that one of the most important aspects of becoming harder to trick is knowing how easy you are to trick. You can't be too smug about it; that's how the skill erodes.
So people who are hard to trick end up seeming to lack confidence, and people who are either easy to trick, or are tricksters themselves, are brimming with confidence. And confidence socially plays as a sign that you know what you're talking about.