I agree that no analogy is perfect but that particular one would be as close to perfect as an analogy could be if my dog could speak. If my dog approached me when I was hanging out with my buddy and threatened to tell my buddy what he had seen me doing in the other room, to be honest, I would flip out on him too. He's supposed to be my friend. Man's best friend, and it's hardly my fault he walked in on me when I thought he was sleeping on the couch.
Just because you don't perceive something, it means people who did notice it are wrong?
It's probably not the most popular opinion here but I agree with your friends. If my dog accidentally watches me masturbate and my buddy stops by afterwards, and noticed the dog is acting strangely which he almost always does, my buddy doesn't know why and he will never know why. Only dog knows.