I car was pulled over in front of my house a while back and they brought the dog out. As it was sniffing around I saw the cop tap his thigh and the dog instantly sat down. They then proceeded to search the whole car. Lucky for them they really didn't have anything and were let go.

Which right off the bat should show drug dogs should not be used. How do you get a "hit" but not come up with anything and still act like it's a viable tool?

I get breathalyzer aren't enough to convict an an owi but are enough to take a blood sample. But breathalyzer don't lie about alcohol only the amount. You can't make the breathalyzer ding you on command.