It's not what you say, it's how you say it.

Let's face it. More and more and more of our communication happens online or in text of some sort. Text messages, emails, messaging, tweets, the whole nine yards. I'd estimate that probably >60% of my communication happens in some sort of text format, with some days higher than others. And I know that's not uncommon, especially for others in the tech field.

I think that's why when I come across someone who doesn't pay attention to spelling, grammar, and capitalization, it really gets underneath my skin. I'm not afraid to say it; I think less of that person. I've heard excuses from "well, my fingers get ahead of my brain or vice versa" to "well, these computers are still a new thing in my lifetime, so people don't expect perfection." Both of them are true, I don't disagree. I think we can all relate to when we're quickly hammering out an email or tweet and miss words or punctuation. I know I'm guilty of it from time to time. Likewise, people don't often expect perfection. But what they do expect is readability.

Text has some inherent problems. Tone, inflection, and often meaning are lost when words are written instead of spoken. Different fonts or styles can be used to convey meaning, but that only goes so far. Sarcasm almost never translates, hence a rise of the use of /s to denote the end of a sarcastic statement. If even a well written sentence can lose meaning, imagine how much more is lost when someone can barely understand what you were trying to say.

I'm not saying we have to be perfect in our online communication, but people look for 3 main things when they're reading:

Spelling. In this day and age of spell check everywhere, there is no excuse for misspellings. If there's a word that you just can't remember, plug it into Google. It'll probably say "did you mean X?" and there you go.
Punctuation. Sometimes I can't figure out if someone just sent me 3 sentences or one horribly mangled sentence or some sort of freeform poetry. Sentences end in periods. The word "don't" has an apostrophe in it. Same with can't, won't, and haven't. There are rules to these things. Follow them.
Capitalization. When you're talking about yourself, I is capitalized. Always. When you start a new sentence, that first word is capitalized. Proper nouns, like that vendor you were talking about? Yeah, those are capitalized too. You're not E. E. Cummings, it's not an expression of yourself. It's an email to your boss, capitalize your words.
I know I got a little ranty there, but isn't that what blogs are for? If you, or someone you know needs some help on some of these, maybe you're a little unfamiliar with some of those rules that I was talking about, I suggest Strunk and White's "Elements of Style."

And please, for everyone's sake, take those extra few seconds after composing your tweet, email, or message and save some brain cells for the people on the other end. Doing just those few little things will make your communication seem more professional, easier to understand, and people will think you're smarter for it. Or at least they won't think you're dumber for it.