Well, I have issues galore concerning grammar, English and punctuation. I have carried a dictionary with me since I discovered the necessity. I then bought a spell checker, an electronic one. Now I write everything I wish to have read and understood by others on Word, check the basics, cut and paste to the area I wish to post. Just as I have with this very one. It is an issue with me to attempt to correct myself not to offend or demean others. Some folks are very good with spelling and the like; I am not one of them. Being the perfect shot, subject matte expert in all things, perfect husband and the best father and grandfather, this world has ever seen takes up most of my time. (HA!)
LOL....I have not attained perfection in many things...not that I haven't tried....but correct grammar and spelling are huge loves of mine. My posts here are usually long, and I reread them and proofread them countless times before posting in nearly all cases. I'm up to at least the 10th time I have "Previewed Post" on this post. Sometimes I will reread them several days later to make sure.
I am an accuracy freak too, and I might spend two or three hours, occasionally more, on a long post, researching all aspects of what I am writing about for accuracy and checking for grammar and spelling. If I have to leave before finishing the post, I will usually cut and paste it to Wordpad or to Word.
I did the Word thing as you do for several years, back when I first discovered the 'net, and always did it during the 10 years or so that I was an internet writer. (I wrote articles and product reviews for three PC hardware websites, spent most of those years writing over 10,000 words a week, along with posting essays mostly on historical topics, occasionally entering essay contests, running a blog, and being an active member on up to a dozen or so forums. The internet was my second 40+ hour job and I didn't make a cent off of it.) Actually, Word and other word processors, but especially Word, inject a lot of garbage that you may or may not see into the HTML. I actually was asked by one website owner to please not use a word processor, and he actually put a draft function both in the article section and the forum section of his website mostly for me. His online HTML editor was one of the most horrible things I have used for writing articles.
I think that it really doesn't make much difference now, unless someone is using an old hooptie computer with a browser that has never been updated. But any garbage in the HTML on any page, whether or not it was injected by a word processor or standalone HTML editor, or just a mistake in the HTML, wreaks havoc on any ancient browser. Firefox, IE 9 and IE 10, Google Chrome, etc, all are configured to constantly look for mistakes in HTML and the other parts of a webpage, and constantly make corrections to enhance your browsing experience.
As far as for the original question....it irks me to no ends. I can live with a spelling error or two, and maybe a grammatical error, but this day of texting into a forum or typing just enough that you think you are getting your point across totally drives me nuts.
But, I have learned to overlook it after spending my first several years on the internet criticizing people for it in email groups, bulletin boards, newsgroups, and in the early forums. By 2003 or so I had pretty much stopped it altogether, except for the occasional totally garbled post. I think that I actually defended justxboxin once for his lack of capitalization, punctuation, proper grammar, correct spelling, etc. Guess I'm getting mellow in my old age lol.