Me too. You end up feeling ambushed, because you'll be reading a bunch of witty, smart, and/or playful comments on some Reddit post, thinking "I don't know these people but they're fun", and then you randomly encounter some unchallenged misogyny or racism in the midst of it with plenty of upvotes. Can these people really exist? Do I want to even be reading something that people who repulse me are also reading?
If you stick to subreddits thing are much better. For example, I lurk on r/rust a lot, and like other high-quality subreddits they have a stickied code of conduct to establish the ground rules. And the community there is extremely friendly and encouraging.