I get some documents at work that I have to work hard to restrain myself from sending back with red pen all over them. Subsequently, the author of one in particular pointed out something that wasn't even wrong on one of mine...
8/10 for me. But then I never was any good at English. I was in the CSE class where they didn't teach grammar. In tests I would always get a maximum 10 marks deducted for incorrect spelling/punctuation etc. I had to retake the exam to get an O Level pass.