1) One who exhibits judging events, comments, news and anything that will stir negative responses from other Facebook friends. Passive-Aggressive tendencies.
2) A person who likes a particular topic, or posts a link, then comments on it for the sole purpose of being a negative prick/or bitch. A ego-centric individual that is driven by sadistic tendencies, and mostly thinks of ones own self, without regarding how comments may effect others.
3) Person who lacks depth, empathy, and character.
Closely related to Facebook Narcissism
"Facebook Critic" is someone that posts, or comments on topics like politics and religion, knowing they will only stir negative responses sooner or later.
John: "Atheist's are full of Shit!"
Larry: "OK John, why are we full of Shit?"
Sue: " How about that Republican debate last night, what a bunch of losers!"
Jane: "@Sue, so Democrats are all winners?"