I'd walk up to him and say "is that the best you can do" and walk away.
While most of us here are not professional writers, mistakes will happen. However, using a spell check/grammar check program before submitting the story would help reduce the errors. Stories with errors just turn me off. I am not a "grammar nazi" but I do believe that everyone should take pride in their work. Submitting stories which have grammatical or spelling errors is not showing pride of work.