Most people trust their gut. I think it is because one's gut is usually right. On a technical level, a gut is a collection of prejudices, biases, and pattern matching -- and that turns out generally to be correct. So your gut is usually right (certainly more than 50% of the time). But 100%?
So … should you trust your gut?
I think some people have an unusually good gut and they should trust their gut. But my guess is that most people think they have a better gut then they do.
I personally don’t trust my gut … especially not with people. I often find that when I meet someone I judge them wrong. I'm an optimist and I often over-estimate people. Sometimes I under-estimate people and am pleasantly surprised.
Hiring is an area that I never trust my gut. In fact, most of my bad hires in past have been because I went with my gut instead of taking the time to use real analytics.
And while I love the book Blink (by Malcolm Gladwell), I don’t think the split-second decisions are always the best ones. Especially on non-obvious things. For instance, I love math and probability problems (especially the Monty Hall problem) -- and "gut" answer is almost always wrong. In the case of the Monty Hall problem, almost everyone I have ever asked gives the wrong answer (there are only two choices -- so it is weird that 98% of people pick the wrong choice) … and when I ask them why they are picking their choice, they usually answer "gut."
That is not to say there is no place for a gut … there is likely a good place if you truly have a good one. But for an analytical person like me, rock beats scissors and brain beats gut.