Did Rover seem to hate your ex before you did? Does Ginger always seem to bark at that one neighbor and no one else? Apparently, dogs are very judgmental, and your pup may be trying to warn you that this person is not awesome.

Dogs have incredibly keen senses that put ours to shame. They are always taking in tons of sensory information, a great deal of which we cannot see or understand. Because of this, it makes sense to wonder if your dog knows who is good and bad? Well, the answer is yes! Your furry friend knows when people aren’t worth having around.

Dogs are incredibly observant and are watching and studying you constantly, even if it seems like they are just chilling on the couch. Dogs can sense bad people, and there are specific behaviors you can recognize in them when they think someone is uncool.

can dogs sense bad people

Signs They Are Not a Fan

Dogs will show physical signs of discomfort and distrust if they are around a person they consider bad. This can manifest in aggression, fear, or just generally unusual behavior.

Body Language:

  • Growling
  • Barking
  • Ears lowering
  • Tensed jaw
  • Tucking of the tail
  • Baring their teeth
  • Pacing
  • Biting
  • Lunging
  • Hiding

If your dog is acting fearful or agitated around a particular person, they may be scared of them and consider them to be untrustworthy. Keeping your dog around someone that they deem as bad will put them extremely on edge, and they can act extremely out of the ordinary.

Is your typically relaxed dog running around and standing in random places? They could not be a fan of the person they are near. Are they being oddly vocal, whining, and making low growls? The vocal noises could be another sign they feel unsafe.

In awful situations, your pet can become so uncomfortable around a person that they run away, which is every pet owners’ nightmare. This kind of scenario, unfortunately, does happen often. It’s always best to prepare for the worst. GPS-enabled collars with 24/7 tracking capabilities will let you know where your pet is at all times. So if you do run into a bad person and your dog chooses flight over fight, a collar like Fi’s Smart Collar will lead your right to your scared little pup.

It can be hard to know what to look for, but typically any strange behavior is a sign they aren’t happy about something. Knowing the signs can help you judge people along with your dog. Ask yourself, why doesn’t Fido like your new friend? And maybe you’ll start realizing why.

How Do They Know?

There are a few different ways that dogs determine if a person is no good. Some are chemical, while others develop from interactions with an individual.

Are they trustworthy?

Dogs can build and lose trust in humans. Trust is one of the factors they consider when evaluating a person. Studies have found if someone points to a treat but then later points to nothing, the dog loses trust in this individual’s point.

Are they helpful?

Many dogs show their loyalty by disliking people that don’t help their owner with tasks. Studies have proved this to be true. So the next time your dog side-eyes your partner for not helping do the dishes, you’ll know why.

Do they smell bad?

When we react to different situations, our body chemistry reacts with us. Dogs' incredible sense of smell can usually pick up on this shift. This is especially true when people become angry, which makes the dog feel threatened. A puppy's sense of smell will be the first thing to alert them to an unpleasant human before they even meet them.

Judging someone based on their brain chemicals does not apply to psychopaths, since they have little to no changes in brain chemistry to correlate with emotions. So hopefully, you and your pup never run into one!

The Evidence

There have been scientific studies that back up these claims. Research has shown us that dogs understand a great deal and what we do and say, mostly through our body language, which they are experts on reading.

The Gaze

There was a study conducted on dogs’ awareness of human lines of vision and the impact of human eye contact. The study found that dogs are well-aware of the communicative act of directing one’s gaze somewhere.

The human gaze connects with cue-signaling that dogs understand as communication between them and humans. The study highlights that this behavior is present in dogs, while undomesticated canines do not take the human gaze into account.

The Point

Another powerful signal that dogs recognize in humans is finger-pointing. Similar to the line of sight studies, studies conducted on dogs’ understanding of pointing, show they understand the intended communication.

The study also found that pointing is associated with trust for dogs. If the point leads to something positive it builds trust with the person that pointed. But, as the study exemplified, if the point leads to something negative or something deceptive, the dog loses trust in the person and may not follow their finger next time they point.

Can They Sense Good People?

Yes, dogs can totally tell if a person is kind or not. This functions as the opposite of them recognizing bad things in people. They will trust people that help their owners with tasks, those that produce positive chemicals in the brain, and people that offer them things like treats or food.

So just like recognizing a bad person, dogs can tell from body language and brain chemicals if a person is kind and they act accordingly.


The social intelligence of dogs would astound some people. They understand a great deal of what we say and do and interpret it to form lasting opinions on us. From eye contact to hand gestures, dogs are constantly observing humans to understand what we are doing and have a keen sense of who is good and who is not.

So next time you think it’s cute to play a trick on your dog, consider what they’ll think of you.