I'm sure it is all relative, but here's a clue: I'm a parent of a Mudder and one day over winter break I was working out at my gym wearing a Mudd t-shirt. A young man approached me and asked if I had a student at Mudd. I said yes - he said he was a student at Claremont-McKenna College and that Mudd had the best parties out of all the Claremont colleges. He apparently just needed to share that with me.
Not sure how much partying goes on though, my student there doesn't really party. I have a feeling it is a good balance of work hard and play hard.
When my D was at accepted student days, the suite she stayed in had liquor bottles lined up all the way along the windowsill for the long row of windows facing the outward courtyard. At least that one dorm has a party reputation -- honestly don't recall which one it is, it is the one D was in for her overnight. She reported no alcohol offered on her overnight, but she also said the current students apparently had gotten a lecture (possibly saying they are a small school and the administration WILL hear if someone does something inappropriate for accepted students days). But my D certainly did not come away with the impression that the campus is dry!
Some people party all the time, and yes, some dorms have many more parties than others. Other people spend Saturday nights playing video games, watching movies, or even doing homework. You can get into whatever scene you want. There are at least two dorms that are always quiet and never have parties, and a few dorms with loud music playing and possibly a party every week.
At the Claremont Colleges, there are different kinds of parties. The big parties are the "5C" ones, which anyone in the Claremont colleges can attend. Mudd has one once every couple of weeks. It is usually harder for underage students to get alcohol at these parties because there is more security. There are also parties that only Mudders and other registered guests are invited to.
Mudd has some of the best parties partially because we're engineering students and can come up with and build some cool parties. For example, my dorm always has a glow-in-the-dark pool party with a waterfall. Dorm members built and set up the decks and waterfall for this party themselves (which is a lot of work!).
My son just graduated from Mudd, and Mudd definitely is much more of a party school than I ever would have imagined. What is nice though is that there is no pressure to drink and there are plenty of kids who don't really drink, so if you kid is not into it (which mine wasn't), then its fine. The admin is fairly lax about the drinking as they don't want to drive it underground. Generally, the kids are pretty responsible about drinking (if you can call underage drinking responsible). The dean of students told us they have a lot fewer problems (percentage wise) than when she was at Princeton.
The dorms with more of a drinking culture are West, North and Linde, although I know plenty of kids in those dorms who didn't drink. South and East are more mellow. For most of the outer dorms (like Atwood, Case and Sontage), it all depends on the particular suite mates.
Ive actually done a lot of research for hmc. Ive learned that the best dorm is the north dorm and it is called the jock dorm. Also, the administration is extremely lax about pretty much everything including drinking.
Yes, I am guessing that most of the other dorms would dispute that. I get the impression that the administration puts a fair amount of effort into trying to place first year students in a dorm that matches what they fill out on their housing profile. So "best dorm" for you might be a terrible fit for someone else. For example, my kid really, really does not like sports. So a jock dorm probably wouldn't be a good fit.
Worrying about the "best" dorm and what dorm you might be in is putting the cart before the horse. I would be spending a lot more time thinking about my admissions essays than about that if I were you... you have to get in before this is even a concern.