Do you consider yourself a grammar nazi? Or do you keep silent but you still hate it? Or do you not care at all? Perhaps you're not good at spelling yourself?
Personally, I don't care about spelling where it doesn't really matter, as long as I can understand what it means. For example in text messages, forums, guild chat... What does get me, are mistakes in more 'official' writing. Blog posts, articles on websites, papers...
What about you?