My hearing impaired son is probably an average speller, overall below the rest of his outstanding verbal abilities. I assume it is because he doesn't always hear the ends of words. I do 10 spelling words a week, putting them on notecards and briefly going over them daily.
He has an almost photographic memory.
I personally think being a poor speller reflects poorly on the person- it makes others thing you are uneducated, not simply a poor speller.
Our school really doesn't emphasize spelling either.