I had a roommate in Las Vegas who used to smoke crystal. I walked in on that a few times. He was kicked out of student housing for getting caught smoking weed on the roof of our building, of all things. Can't say I was sad to see him go.
In the last year, between VT and NYC, I've been around weed (everywhere up here), coke, crushed adderall, molly, and 2C-I. I have two acquaintances who love acid and shrooms but I haven't been present for those. Perhaps surprisingly, these are all used by extremely intelligent and well-adjusted people including Dartmouth and Cornell grads, an MD, some PhDs, other professionals. The people you meet!
On a slightly darker note, my little town supposedly has had a bit of a heroin problem, and the house across the intersection from mine was raided two weeks before I moved in. I haven't heard of a single issue with it since, as my neighborhood consists of mostly young families and a literal hippie commune with lots of kids, but I did find a capped insulin syringe loaded with a clear liquid on the sidewalk (not on my street) a few weeks ago.