Everyone here knows how I dislike poor spelling but I will never refer to anyone who can't spell as stupid.
You will also know that I know I have strengths and weaknesses. There are many things I can't do that bad spellers may be able to do.
However, if you are applying for a job and you know you can't spell, get someone else to proof read it.
(Yes, I know I should have used "one", not "you".) I've done that for many of my staff over the years.
As Edd (George130) pointed out,
a dictionary is not much use for a bad speller. If one can't spell at all, how does one look up a word? Help is at hand. One can buy bad speller's dictionaries which, I assume, spell words incorrectly and shows the correct spelling. There are a number available. For example:
Webster's Bad Spellers Dictionary Review - Eclectic Homeschool Online
The on line Webster dictionary is good in that if you can't spell, it will offer suggestions. Try it:
Dictionary and Thesaurus - Merriam-Webster Online