Even back in the era when reading resumes and hiring was a manual human process, the standard advice was that resumes should be perfect. Nicely formatted, with no spelling or grammatical errors. You have ample time to think about the content, to proofread it yourself, and to have someone else proofread it. It's the first impression the potential employer has of you, no reason to not make an effort.
I'm not sure that's true at all. Coming out of school pre-Web when real information was much harder to come by (even job postings), I sprayed and prayed a lot of resumes to HR departments. (And my first engineering job came through one of those.)
