My friends have told me stories wherein their dog was able to sniff someone out. For instance, one of my friends used to date this guy that she met from a real singles tour and had him over frequently at her apartment. Her dog used to behave really strangely towards him, like barking, growling, and generally showing aggressive behavior. Now, that dog is usually very sweet and friendly, so it was really weird.

Later on, my friend found out that guy actually lied to her about his age, job, and everything about his background. So I was wondering, do dogs really have intuition? Has anyone of you ever had a dog that acted strangely around a person you know, only to find out later on that their intuition was right about that person all along?