Dog senses

Believe it or not, there is a very simple and easy scientific explanation as to why your pup can sense a bad person or a person with bad intentions. When a person has bad intentions, act in a bad or negative way, or have evil feelings or thoughts, the human brain transmits and releases certain chemicals. For instance, if someone is about to do something bad, adrenaline increases and, in turn, makes the person sweat much more than normal. Since dogs have a very keen sense of smell, they are able to pick up on these scents and changes within a few seconds and react to them. The dog's instincts kick into gear and they become more alert and aware of what is around them. If they are sensing something out of the ordinary, either fear or protection/aggression will manifest in their actions and demeanor.

Read more at: https://wagwalking.com/sense/can-dogs-sense-bad-people