I notice spelling errors. Without trying. My brain is just wired to notice. I can spell very well but my pronunciation is not that great.
It doesn't matter. If the blogger gets the message across without detracting from the message because of slight spelling or grammatical errors, if you know what I mean when I write it, then it doesn't matter.
Why are you wasting your precious time sending a comment to a blogger to point out a spelling error on a post that's a week old? Or even an hour old? Who cares?
Stop wasting your time with the trivial matters and start living.