"Pepper, Perfume and other scents have no effect on the dogs."
That is also what I understand although I don't know much about the subject. I am basing this on the fact that I am a firefighter and our department has arson dogs. The dog handlers gave us a class in the academy and said that dogs smell things differently than humans. They smell component parts of things (for the lack of another way to put it). For example, if you and I smell pizza, we think: pizza. When a dog smells pizza, it smells tomato sauce, pepperoni, mushrooms, onions, etc. So, if you put black pepper around your car, the dog would smell black pepper, gasoline, oil, human, gun, cigarettes................
Our arson dogs scent stuff used to start fires like gasoline. The fact that walk into a burnt out building with smoke and steam still rising from the structure, they can easily detect gasoline or whatever: after that chemical has burned or not. I am sure that most houses have black pepper, perfume, cleaning supplies, etc in addition to the powerful smells associated with the fire. Doesn't bother the dog at all. It also doesn't bother the process that people keep things like gasoline in their houses normally. The investigator simply uses common sense to rule out arson even though the dog scents something. For example, the dog scents gasoline in the garage: that would be normal. The dog scents gasoline in the master bedroom, on the bottom of a pair of shoes: that would also be normal. Dog scents gasoline in multiple spots around the living room consistent with the burn patterns on the walls: you are in deep do-do.
Do you realize that there are dogs that find drowning victims underwater by scenting the air while riding in a boat ?
I once read a story about a kidnapping in Germany. The police found the getaway car several days or weeks after the fact. They laid a piece of cloth on the car seat for awile and then put the cloth in a glass jar. A couple years later they narrowed the case down to a couple suspects. They brought them in for a line up. They took out the piece of cloth, let a K9 smell it and the dog walked right over to the guy that did it: years later.
Another thing to keep in mind if the dog is being used by a police department or one of our arson dogs: those dogs are considered to be police officers. If you screw around and injure that dog, it is considered the same as if you had injured a human police officer and you will be punished accordingly. I would bet money that if you injured a dog owned by a private security company (or they say you did) you would be fired or possibly even sued for damages. I am all for personal freedom, gun ownership etc. Part of that freedom is the right to tell people what they can and cannot do on YOUR property as well as expecting that people who do not follow your rules on your property or people who damage your property to be punished.