> "The good news is that I've recently returned to 4chan as a regular, anonymous user, and I'm really enjoying it."
> I've never visited the site, and really don't want to. So maybe I'm missing something, but why would you want to associate yourself with a place like that?
> I see people post screenshots on Reddit sometimes and it seems pretty deviant.
As depicted in some screenshots people post on Reddit. (One thing that helps: look at the background of the screenshot. By default, a blue background indicates a "safe for work" board, and that's well-known enough that people sometimes use the term "blue board".) And yeah, a subset of it is, including several entire boards.
4chan features the full gamut of what you could expect from the Internet, or humanity in general. The quote about Usenet and "a herd of performing elephants" applies quite well there. And like the broader Internet and culture in general, the quality of content varies massively.
However, the bet of what 4chan has to offer includes some amazing content, much of it original, and only a small subset of that makes it to the outside world. A huge number of Internet memes start there. People create impressive original art, sometimes drawn on the fly and posted in response to others nearly in real-time. Despite the name "image board", people write and share huge walls of text there too. People tell stories ranging from side-splittingly hilarious to heartwarming. (Yes, really, 4chan can do "heartwarming" on occasion.) And much of the best content gets saved in screenshots, files, and wikis, and re-posted later. (Its transient nature has as much to do with its culture as its anonymity.)
For one of many examples, the tabletop gaming board /tg/ has quite an impressive array of content. People develop campaigns and settings there, run games on the board, design games, produce interesting original writing, post stories of gaming adventures, and otherwise produce an astonishing amount of original content. You can go there if you run a game and you're looking for material or inspiration, or if you just want to laugh at a pile of nerdy jokes and enjoy some interesting stories. And note that /tg/ is considered a "safe for work" board, and the moderators do enforce that.
Also see the TED talk from Christopher Poole ("moot"), which mentions several more interesting stories.
4chan does have a large amount of "background radiation" to ignore, and portions of its culture can be quite toxic. It's not in any way a curated collection of content. But parts of it can be awe-inspiring, useful, and fun.