According to recruiters, too many candidates are let down by their sloppy writing skills.
Shakespeare made up words, spelt his name however he pleased and is still praised for his mastery of language. However, if his cover letter was written along those lines today, every law firm would bin his application. All recruiters say the same thing; simple errors in spelling and grammar derail otherwise competitive applications. But perfect spelling and grammar are not the only factors that make a good application.