Should I always listen to my gut feeling/intuition? (especially about people)
Do not trust your feelings!
Your intuition is all over the place and has no idea what’s going on. Intuition is like common sense; nebulous, useless, and sometimes a justification for lazy decisions or badly thought-out opinions.
Your gut lies to you! It is designed to process food into energy and building materials, not deliver wisdom. Your gut is wrong all the time about everything.
That’s facetious, but you should be careful about leaning on your intuition; these feelings are not beamed into your head from the mothership. Everything is coming from your own thought processes, and you should decide for yourself if those processes are useful or not.
For instance, many people strongly feel that vaccines harm children. It’s understandable why any parent would balk at injecting a child with enervated diseases, but vaccines have been demonstrated to be the best way to prevent all sorts of horrific childhood diseases and vaccines are among the safest medical products available.
The only proven path to reliable information about objectively measurable phenomena is the scientific process: peer-reviewed studies. “Peer-reviewed” means people qualified in your field comb through every tiny bit of your work in an effort to prove you wrong. The scientific process has given us electric grids and modern agriculture and plastics and hearing aids and computers and antibiotics and X-rays and satellites.
And vaccines.
Although if you get an icky feeling about someone and you're not sure why, maybe just steer clear of that person. It's hard to walk back the ick.