Why not just stick with the old adage, “If you can’t say something nice; say nothing at all.”
What if sometimes you really need to tell them that they are %$&@*(&$@#)? Are you telling me you'd be all sweet to someone like Osama?!

Sometimes there is a need to insult someone. A good poster is someone who can insult you and you'd thank them for it (the old good flames that use to occur on news groups are prime examples of this).
And always remember
Godwin's Law.
(I remember the "good ol' days" of the internet when people actually knew how to spell and I didn't have to decipher their "leet" message -- a specific peeve of mine since I get occassional essays written entirely in IM).