I don't, it's a place for people to unleash their true selves. Not worrying about finding friends, family, social rules, the law in many cases and it's free
Not many websites can claim this and that is why 4chan gets a lot of respect from me, it's freedom of speech actually being used. The people on their aren't freaks, they're people just like you or me being as moronic, angry, horny etc as they like because they have nothing to lose
Even if you don't go to /b/ the other forums are useful such as /fit/ and /g/