Like many others coming from social web, you expect to find some kind of community which fashions everyone shares, an apparel you can put on. The idea is complete opposite: you don't need to follow any fashion, or imagine yourself “part of the team” any more than you want to. Even though it's not written in any rules, you don't have to use slang or tone if you find them dumb, overused (globally or locally), or forced. Neither do you have to treat stupid posts with respect.

I assume that after 15-20 years of being part of collective consciousness, anonymous image boards have mostly the same public as any average site. Amount of crap that you can read there is just the same as everywhere (though in some cases this or that Big Brother hides it from your view — obviously, to make you more comfortable, and spend more time in his warm embrace). The difference is that regular social fashions mandate the use of suitable set of candy wrappers for the crap, then there are customary ways of dealing with them, so in the end people just spend their time wrapping and unwrapping crap, but are proud of themselves, and call it “civilised discourse”.