system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 : Why do we get some kind of negative vibes when we are around certain people?
gpt
It's an instinct that is supposed to protect us.  The specifics on what it is protecting us from can vary from one situation to another.

On a very primitive level, a person who is unhappy or unpleasant may be unhappy because of a disease.  Diseases can be contagious, so our instincts tell us to avoid them.

On a more social level, think of it in terms of individuals within a primitive tribe.  The people who are unhappy are likely to be the ones with poor access to resources, and therefore probably have less useful talents, and therefore there is less reason to learn from them or spend time around them.  So our instincts tell us not to.

There is also the issue that people with difficulty in their lives may be more likely to behave aggressively than those who are healthy and prosperous.  Our instincts tell us to be wary around them for this reason as well.

Not all of these things will necessarily be relevant today or in all circumstances, but our instincts are very old and mostly focused on helping us survive, which is not always the same as being nice.