Originally posted by RuiC
sarcasm
A tongue of which the user speaks of something the complete opposite of what the user means. It often has the best comedic value.
That's actually irony. Sarcasm is the use of irony to show contempt, whereas irony is intended either to convey a hidden message or, as you suggest, for comedic effect. It seems to me that very few Forum members here have contempt for Pentax or Ricoh, but many see the humour in the situation. Those who are contemptuous don't tend to stick around, but brag about their Nikon/Sony/MFT acquisitions for a little while and then depart, perhaps to vent their personal issues elsewhere, perhaps to happier audiences.
Still, in this Mad Hatter linguistic world we live in, meanings can change as quickly as Twitter fads.