It's one thing to make grammatical mistakes here and there, but to make the same grammatical mistake hurts my eyes. For example, I read someone's online posts where they repeated the use of "your" instead of "you're" about five times. I am going to be honest: I think the person is dumb.

So, while this instance was not a professional setting, if you took the time to write something and have the chance to edit -- why not write properly?