After 20+ years of work plus extensive world travel off the beaten path, I'm very sensitive to my instincts. I always go with my gut when I sense a creepy person and make it a point to move on asap. There still has to be more though, but it's a good start to learning more about why we react more to some people.
A friend that I used to work with in DC had once told me a story about a man who she had met on a few occasions at social events. He was of her father's generation and while polite, he always gave her the creeps. A few years later after a regime change in the Middle East, she was back in her birth country and saw a photo of the creepy guy on TV during a report.
According to the TV report, the creepy guy was the official torture director for the ousted regime and they were exposing his full history. Somehow that story never made it (publicly) to the West, where he lived comfortably after the regime change.
It is fascinating to see that researchers are now confirming this type of information.
In one trial, a researcher attempted to be friendly with participants as if they were peers. Sometimes the researcher moved like the subject; if the participant touched his nose, the researcher would gesture similarly, such as scratching her head. But in other cases, the researcher would not mirror the subject’s actions. And this caused the participants’ skin to crawl -- if the researcher did not mimic the right cues, the subjects reported feeling colder. Creepers give us the chills. People believed the room temperature dropped to 68 when it remained at a steady 72.
“In the friendly situation, if you do not mimic, that’s when people’s coldness spikes,” Leander explains. “If you start feeling cold it could be an early warning sign.”
When people violate social norms, our bodies react with chills. Feeling cold is linked to a threat such as being forgotten (think left out in the cold") and the region of the brain that controls goosebumps also regulates feelings of trust and betrayal. The chills warn that something is off about a person who cannot follow social norms.