A pet peeve of mine is grammatical errors. I don't mind when it's in a Facebook status, a text message, or online chat - but when professional presentations have these errors, something is wrong.
In one of my classes, we had the career center come to talk to us about opportunities for English majors. The presentation and presenter were specifically targeting English classes, yet the presentation had multiple grammar errors. I sent a polite email to the presenter afterwards, pointing out the errors so that she could fix them for using the presentation later. I never got a reply, which implies to me that she didn't care enough to fix it. Why should I put my trust in an English guidance presentation when it doesn't even use correct English grammar?
Another interesting example was a news article from MSNBC. The article must have gone past at least one editor, and probably multiple ones, and no one caught the errors. Errors I often see in news articles are missing periods, misuse of homonyms, and sometimes missing important punctuation marks such as closing parentheses or quotation marks. As somebody aspiring to be an editor, it's frustrating to see that multiple editors aren't doing their job well consistently. Media requires trust to operate, but it's hard for me to consider a site reputable when the editors don't catch important grammatical errors.
I don't mind when grammar is incorrect in casual situations like talking to friends, but with any work that is going to be presented to others it isn't hard to find people willing to read it over to catch mistakes. In presentations for classes or work, correct grammar is even more important. Incorrect grammar looks sloppy, and can even lead to the presenter looking less intelligent or capable, especially in work situations. It can lead to not getting that promotion, or getting assigned less important work that doesn't exemplify your capability, which ends with not getting a chance at a promotion in the first place. Obviously, a single missing period won't affect anything too much, but multiple grammatical mistakes are not something to take lightly.
There are people who will look over work if asked. There are sites that list common grammar mistakes that can be looked up if you're ever unsure about a rule. Rereading a work that will be turned in or presented usually results in discovering at least some of the mistakes. Grammar is important.
