At some point in my brain there was established a very strong connection between people who knew how to use language correctly and people who were actually reasonably intelligent, interesting, and worth talking to. I have found plenty of counterexamples – but not enough to sway that first gut reaction to “cum on giveme a BReak ppl Im new hear???”
I'm not asking for Oxford-grade English. I'm talking third-grade competency here. Things like Not Capitalizing Every Word In A Sentence Unless It's A Newspaper Headline. Things like not sticking random apostrophe's in plural noun's (*shudder* it hurt to write that). It'd be nice if more people knew what the subjunctive was - but I'll settle for them knowing the difference between a statement and a question.
I've tried to be more forgiving of bad spelling; especially in informal fora like IM and LiveJournal. Hell, I often dispense with capitals on LJ - I'm sure I've made the occasional spelling error, and I misuse "hopefully" all the time. I'm not exactly sure where the line is, but I know there's a point where the medium is being abused so badly that I will barely notice the content. And don't get me started on hAx0r. Ye gods. It's communication, not a cryptogram!
There's always the functionalist argument: as long as the meaning is conveyed, what does it matter if the grammar and spelling don't strictly abide by a system of rules which is inherently inconsistent and dynamic anyway? Given that I use the same argument in many other contexts, I find this one hard to combat directly, but I think I come down to this:
Before you break the rules, know what they are and why they're there. Language is a medium of communication; and if you follow rules that everyone knows (or at least can look up somewhere) then the communication is much more efficient, with less room for misinterpretation. I'm all for chaos – but let's have it be intelligent and educated chaos, shall we?