I have to admit that poor spelling is one of the things that just bugs me no end. In my job, I have to write engineering reports all the time and the ability to make yourself understood is essential. Also, being a product of 1960's elementary school, spelling was something that was drummed into your head. Misspelling is so commonplace anymore that it's noticed less and less. Apostrophes where they shouldn't be, no punctuation, and generally poor sentence structure are things I notice daily.
"I tried hard to not loose my keys. But, I went ahead and lossed them anyway."