Even online, when you can preview what you've written and take out all the adverbs, spelling mistakes and split infinitives, a certain amount of doubt creeps in. Thus all of the "hedging your bets" acronyms like AFAIK, IIRC, YMMV, IMO/IMHO/IMNSHO, and their ilk. At times I feel impatient with this. "Just my opinion" — well, who the hell else's could it be? 
Another difficulty is that online, no one can see the expression on your face, and unless half your post is smileys, there's uncertainty about whether the reader will take it as you intended. We word things so that no one could possibly misinterpret, yet even then we doubt. (And even then, people can and do misinterpret.)
One answer, as Hadron says, is deliberate ambiguity, which can be great fun when skillfully executed. Take Calandale for instance, he excels at ambiguity. "No one deserves me." That's delicious! So many different ways of taking that! It's a game to toss out something murky and see which way people jump.
Ha - you know Cal more or less taught me, right? Though I was on the right track to begin with, so to speak.
