All those shows like on A&E and shit really show the most exaggerated extremes of how people on drugs practically exude the essence of their drug use in every thing they do. But in reality, shit... I'll bet you've interacted with hundreds of people on drug combos that you'd sooner believe would kill a horse without even noticing it. Because addiction can happen to anyone, it's usually the last people who should be using certain drugs that make them look so parasitic and all consuming. But it can also happen to people in the way that taking Insulin every day keeps a diabetic going. There's inherent risks to it but the truth is most drug use or addiction is hidden and often by highly functional people. It's the kind of thing a person can hide from their own family and even keep up so effectively at times that they fool themselves into forgetting that they're hooked. But the reality is that it's so much more pedestrian and normal than we've been lead to believe.