I think one of the biggest annoyances, ESPECIALLY in the professional world, is poor spelling and grammar. This is even more obnoxious when the aforementioned faux paus are done in electronic documents.
The problem is people are lazy...yes, lazy. I have come to find that many do not proof read a document before it is posted, sent out, etc. These individuals rely solely on spell/grammar check. Someone needs to create a program smart enough to know when you are using the improper form of a word; there, their; where, wear; so on and so forth.
Please don't use a word if you don't understand the meaning. This happens far too often for my taste and it isn't getting any better. I appreciate the desire to use larger words to sound more intelligent or 'grown-up', but really, saying "The sky is blue. That's ironic." doesn't make you sound any smarter, and, actually it probably makes the people around you dumber.
The other issue that really gets to me is made up words/contractions. I have seen the use of improper contractions so many times; I want to pull my hair out.
I know we are an intelligent community of people and I like to think there is still hope out there for humanity.
Perhaps, some may say, we should look to the educational community and have them step up their game. Alas, they are not the only ones at fault with regards to this dilemma, which is now approaching epidemic status. We, as a society, tend to be lazy with our speech; we cut words short, text in acronyms, and speak in slang terminology. These things aren't necessarily a problem until you encounter a 'professional' environment. I will admit that I text in acronyms and have been known to use slang (cheese* haha), but, like all things, there is a time and a place. I would like to say that I'm not attempting to make anyone feel bad nor is this directed at any one person. This is a blanket annoyance. For example, every once in a while my husband uses poor English. I don't judge him or correct him because he, frankly, doesn't care. Just because I don't say anything, doesn't mean it annoys me any less. =)
I suppose in the grand scheme of the world, if this is the biggest concern in my daily life, I'm doing pretty well. However, on those days that I am particularly critical, this issue is really obscene.
::getting off my soap box now::
*cheese: inside joke