It is difficult to discern "intent" in text.
That's why we have these guys-->
Meet the emoticon.
Confusion is understandable online, D.
I tend to be both sensitive and inclined to sarcasm--and I still "slip". I still find myself being misunderstood, and I also find myself misunderstanding intent.
The best thing to do, though, is ask.
When I get stuff wrong, I apologize.
When I unintentionally hurt someone, I apologize.
Sometimes I even apologize for apologizing too much.
Then there is my tendency to over-explain m'self too. (Sorry about that folks.)
(See? That was sarcasm, but well-intentioned as a little joke, as indicated by the *winking smilie*)
Hope that helps.