I guess there is a great difference between "normal" life and "online" life. In a chat or forum I'd accept almost anything. Wrong spelling, shortcuts, wrong grammar, wrong words.... Especially because there are people with a different mother-tongue.
But concerning "normal" life (school, business...) I can't stand such expressions. And I paticularly loath them in stories. Although I try to be patient with grammar or not quite fitting words. I tend to have those problems myself, since I'm not a native speaker.
Also I disagree with Mobius. The use of a spell-checker is sometimes not the worst option. It helps me, for instance, to improve my English and to avoid the most popular mistakes.