Most UC students don't seem to know much about the drug scene, mostly because there aren't a lot of drugs on campus. But, just because it isn't there, doesn't mean it isn't happening somewhere nearby. A lot of off-campus parties have pot around, but smokers won't pressure you to do it. If you want some, most people are cool about sharing, and they don't make a big deal about it. They're also relatively open with their peers that they smoke, and many times you'll hear people talking about the last time they got high or how they plan on getting high later. Smokers also will tell you that it's easy to get pot in Clifton.
Students say they very rarely hear about mushrooms, crystal meth, heroin, cocaine, or other "hard" drugs, so it seems the drug scene overall is very minimal. If anything, the drugs that do exist are off campus because the dorms tend to be more strict and harder to sneak things in. In general, there isn't really a "scene" at UC.