I shared a house back in college with a guy that had a dog. We lived out in the country down a long driveway. Friends would come over, knock on the door and the dog wouldn’t bark (even if they just kocked and walked in). For strangers, the dog would bark once or twice as they were coming down the driveway to let you know someone was coming.
Except for the Jehovah’s Witness folks. They would come down the drive and that dog would start barking non-stop. By the time they kocked on the door she would be barking, growling, snarling right at the door - had to hold her by the collar to keep her from going through the screen. That happened 3 or 4 times in the two years I was there. REALLY weird!
Even the Mormons just got the 2 bark response!