Many people who read résumés say that they stop reading as soon as they see the first spelling or grammatical mistake. They say that there is no excuse for these errors now that we all use word processors equipped with adjunct software capable of exposing our mistakes. I believe their point is that marketing documents are so important that job applicants should be expected to exert every possible effort to achieve perfection.
My position is that very few jobs require perfect spelling or perfect grammar, or even good spelling or good grammar. Not only that, when you discard applications on the basis of spelling or grammar you are almost certainly discarding some that would achieve good results in the measures that are of actual interest to you as an employer. Before you review a stack of résumés decide what performance you need from the new incumbent and judge accordingly.
I have been prompted to write this item by an item in the CBC News: [Jane] Austen was bad speller: U.K. scholar. Austen the treasured author! Even her spelling and grammar didn't matter (that much) because it could be corrected by an editor.