It's real hard to tell if somebody is on a moderate amount of opiates, even if you are an "expert" at it. When they are on a huge dose of course they are "nodding out" and can barely put a sentence together, and any fool can tell they are high. But on smaller doses the addict learns to hide it really well. It's not easy to judge somebody's pupils because you can't really see somebody's eyes unless you have good light, and guess what--when you're in bright light everybody's pupils become tiny.