Why Dogs Bark at Some People But Not at Others

1. Unknown is scary.

The most common reason why your dog reacts to certain people poorly is because it’s experiencing something new. If the dog isn’t properly socialized, every exposure to strangers — and with it, a bunch of recent smells, sights, and behavior — can seem threatening for the animal. whether or not the dog is socialized, it can still find itself in a very situation where it feels anxious and insecure about something unfamiliar.

So the dog is more likely to bark at the those that possess more unfamiliar traits, especially when it involves smell and appears.