I know, that's asking for it. The nasty putdowns write themselves.
Actually, it was a cheap putdown that inspired me to write this. I saw this in Facebook the other day: "Don't trust your gut; it's literally full of shit." Ha ha. And then, not wanting to be humiliated by any more such wit, we abandon our views out of fear.
And, you may think, my gut instincts are often wrong. That's true but they are also often right. So, what do you do?
I'd suggest not thinking about the issue in terms of right and wrong. Think instead that you are your gut.
Good Cartesian dualists that we are, we tend to think of thought as something that happens in the brain. Many of our ancestors imagined thought happened in their bowels or in their chests. The Psalms were all written by people who imagined thought happened in the heart. (As a consequence, we misread them: when we read that we should keep the LORD in our hearts, we imagine that to call for an emotional commitment when it actually calls for an intellectual one.)
Let me give you a sports metaphor. A good male athlete can throw a feint with his shoulders or his hips. He can't throw a fake with is gut. Wherever his gut goes he has to go too. Our gut feelings are like that. They are the accumulation of a lifetime of emotional and mental development. That gut feeling you get tells you that a proposed action either is or is not in your comfort zone. If you feel a vague uneasiness about something, that is telling you that this isn't something you feel comfortable about. When people say, "Trust your gut," they mean that your instincts are a good indicator of what you should and shouldn't do.
I'll go out on a limb and say, without having any evidence, that even if it feels that your gut is often wrong that you would find, if you chose to keep a tally, you'd find your gut is right far more often than it's wrong.
And I'd go further and say, trust your gut because it's you. It's your moral centre of gravity.
Let's ask a different question. How do you get a better gut? Or, to put it another way, how do I get better moral instincts? And here, having put it the way we have, the answer becomes obvious: by developing a better character. Push yourself to improve in small ways that you can clearly see and your gut will get better.
We could turn that around: if it feel like your moral instincts are bad—which is how I felt fifteen years ago when I started this quest—the solution is not to stop trusting your moral instincts. They are, good or bad, the foundation of your moral life. What you need to do is to change what you do. You will become what you do.