My instincts have been wrong before, and it's put my life and physical person in danger. I'm extremely cognizant about where I go and who I let into my house because I absolutely have to be.
For me it depends on the context. In some areas, such as personal safety, my instincts are very good. In the field of cuddling, my instincts have almost always been right so far.
In other areas, such as romance, my instinct usually turns out to be the opposite of the inverse of what would have been the truth had not my instinct incorrectly revealed it to be, conversely, the inverse of the opposite of the truth. Except during the bottom third of the hour of course, when the reverse applies.
I spend the course of a relationship confirming what I gathered in the first ten minutes in the way of body language, word choice, personality type etc. This affects the level of closeness I allow which I tend to regulate with pacing. Between my intuition, journal notes and sometimes outside input, I'm rarely wrong. People can't hide who they are.
I just want to offer a few words of support to anyone who reads this... Follow your gut... your instinct or intuition is something coming from your angels and spirit guides.
I'm sure my instincts have been wrong many times. Giving someone a second chance after they've flaked, only for them to let me down again. But I did once correctly spot a red flag, based on the way she said something. I wasn't sure what the red flag pointed to, but it turned out she had mental issues and had been in a mental health institution. But before I found that out and after I got the red flag she was telling me she loved me, 3 days after first meeting me.