I'm one! I can try, but I have heard that INFJs' version of the self is really different than the way it looks from the outside. I've also heard that INFJs mimic other types, which may make them even harder to spot.
First of all, there are some really good type descriptions out there that you maybe haven't seen:
Personality Junkie INFJ
How to date an INFJ - that one might be good for recognizing infjs?
I know that I come across very very differently to people that I know and people that I have just met. I'm extremely nervous and shy upon first meeting, because I'm very self-conscious about the way that I see the world. Like ENFPs, we're idealists, but unlike ENFPs, we're really really private about who we share our ideas with. If I meet a person and don't think that you fit into my value system, I'll be nice to you certainly, but I won't let you past my guard. The shyness at the beginning is deciding how much of my guard to let down around you, how much I think you want to handle and how much I think you can handle. I really think I'm extremely complex, and I also think that not a lot of people want to see it!
With that said, when you're in (and I super love my ENFP friends!), you're in. I'm playful and not really as serious as I probably came off up there. I love telling stories and making bad puns. My friends tell me that I make them feel healthier - maybe something like WoodsWoman mentioned? I have a few really close friends, and value my family more than anything. I'm really job focused, and I've heard that other INFJs are too- my dad calls it live to work, vs work to live. I want to use myself to make humanity better, and since I'm going to be working however many hours every day, I want to be sure that I'm using that time well.
Serial Killers and Hitler and Stalin are said to be INFJ! So that's terrifying. I know that I have the potential in me for extreme misanthropy. Sometimes I just really think the world is doomed and I feel pretty apathetic about it. (I'm sort of like Tommy the anti-petroleum firefighter from I heart huckabees when he gets depressed and watches monster truck shows). Also, I know that INFJs (particularly enneagram 1s) can get pretty rigid about their value system being the right one, for what that's worth. I guess I'd be interested in other people's opinions about the dark side of INFJs. I have heard that there are like, ass-kicking ones and fluffy ones.