Why should it bother anyone enough to make a judgement of "they don't care?" Why has my spelling been pointed out to me many times when it distracted nothing from the point and the only point made in the reply is my spelling?
Misspellings and grammatical errors can be distracting. When I see people using "their" instead of "they're" or vice-versa, I really have to stop in my tracks and go back to the begining of the phrase to make sure I haven't missundertood something. When I find out I haven't missunderstood anything, I realise I'm dealing with a dope, get annoyed, and feel tempted to skip the post all together. A simple misspelled word isn't that bad, but it does catch my eye, distracts me and makes me loose some time getting back on track.