I once had a coworker call the police on me because I look like a stoner and was smoking a Black and Mild in my car on my break. (One of my regulars love them so I wanted to try it)
The police pulled me over for going 9mph over the limit at 11:30pm... 3 police cars and a K9 unit rolled up and the dog did the alert for drugs. I've literally never smoked weed in my car, and at that point hadn't smoked at all, anywhere, for years.
Moral of the story, if they bring out the dog, they're going to make it give them the "search the car" signal.