Everything I just said is the exact opposite of reality, so yes.

Poe's law explains why sarcasm doesn't work on the internet:

  "Without a blatant display of humor, it is impossible to 
  create a parody of extremism or fundamentalism that 
  someone won't mistake for the real thing." [1]

[1] http://en.wikipedia.org/wiki/Poe's_law

(edit: Poe's Law always reminds me of this SNL skit where Fred Armisen tells Jimmy Fallon that the right way to tell a joke is to use a "catch phrase": http://video.tvguide.com/Saturday+Night+Live/Weekend+Update+...)

Well not exactly: the one(?) form of sarcasm that works very well is when the facts being stated are clearly false. Though obviously this does rely on the audience knowing the factual background...

It relies on more than that. Not only does this rely on the audience to know the factual background, but it also relies on them coming to the conclusion that you also know the factual background and are not just uninformed, misinformed, or plain wrong. Sarcasm on the internet only works well between people who are familiar with one another.

This also relies on a similar cultural background. You'd be surprised at the cultural differences between US/California (a lot of the posters here) and Eastern Europe (my case). And my situation is mild - imagine how this scales between US/California and someone from a completely different culture (China, Africa, India). Actually it doesn't scale at all :)