It's hard to judge people's true overall personalities based on online responses alone- since it's only reflective of minuscule part of their persona and what they go through in their daily lives.
On top of that, some people are better at articulating themselves through writing, others aren't. I know it hasn't been my strength, for sure.
Sometimes people post on forums because they're bored or need an outlet. Sometimes they're in transition phases of their lives.. so naturally, due to a state of uncertainly, they're not going to be in the best of moods all the time.
In other words, situational factors don't reflect overall personality. Real life interactions are a better read (non-verbal communication is just as strong, if not, more communicative than through text).
I agree. Trust people you are closest with. They tend to know us most, second to ourselves. Btw, I voted ENFP.