Thank you all for your input!
It's wonderful to hear so many diverse points of view. I should have put in my previous comment that this shouldn't have been taken to heart.
I am not sure that's a reasonable expectation to have, in Aikiweb, any electronic format, or in face-to-face communications either, for that matter. When you know someone well and they know you well, you might be able to say something negative about their character and then tack on a "Just kidding!" and it will all be laughed off IF they know well and IF your "just kidding" is credible (it won't be if they know you well enough to know that you really meant it and are just trying to dodge the consequences of having said it). It definitely doesn't work when you're talking to strangers or slight acquaintances. That's reality, and it's not a new reality either -- it's always been this way. The internet gives us the ability to presume on short acquaintance in a much more far-reaching way, but it really doesn't make the behavior any more well-received.