Well... wait, I think he can have his say. If he's totally off base, I don't think it's hard to ignore him. But if he's only a little and is honestly asking a question, I don't mind answering, personally, and respect discussion. That's the point of a forum, after all, even one dedicated to INFJ or any other thing. Also, many forums have the capability to set up a block list or ignore list and, if that's how you feel about [MENTION=9401]LucyJr[/MENTION] in general, it is pretty easy to do.
All that having been said...
You lost me when you went from questioning to generalizing. I guess if that is the answer you are comfortable with to your own question, then fine. But if you asked it in a forum I would assume you are interested in other answers as well.
I think what you are talking about is insincere "shock" statements. [MENTION=1871]muir[/MENTION] made a very excellent and subtle point: that your own answer may be a good example of what you're talking about.
Beyond that, though, there's been a lot of articles written trying to understand what psychological affectation causes "Internet trolls", and I can say I'm still utterly baffled by it. Why does someone feel the need to categorically trash what someone else has said or done online without actually addressing what they have said or done online? Are these people getting some sort of pleasure from the superiority of being able to say horrible things anonymously? Are they, in fact, compensating for an "apathic life"? Do they have such fixed generalizations about others that, in the midst of cognitive dissonance, they lash out rather than listen and think?
But I really dislike the idea that this behavior can be attributed directly to an MBTI type. First off, you're probably giving undue approval or consideration to the MBTI types. I really don't think they are as concrete as that "most INFJ's have this horrible behavior or do these terrible things". But second, a specific behavior like this, especially one that can be seen as odious and unjustified, goes along more with a psychological condition that has little to nothing to do with personality. You would never say "INFJs tend to be schizophrenic" for instance, or "INFJs tend to have autism" etc. The condition of schizophrenia or autism has nothing at all to do with personality, or if it does, it is a separate consideration that plays on the personality, not from it.
That's my take. Interested in discussion, as I said, but not generalizations.