I'm pretty sure Snape was an I. He does not exhibit the ebullience and charm that E's are generally able to summon on demand — even an argumentative ENTP. He also lived much of his life in secrecy and in his head.

It seems as though you have only met a few ENFP's and quite possibly only on the internet.

"ENFP's who find themselves in a situation where they are unable to discover and enjoy new people and things tend to get whiny. Really whiny. And manipulative. And possibly passive aggressive. We won't admit to anything. You saw nothing."

I think I may know what your saying, but to those who don't understand MBTI, this is quite narrow and can be said for many other types (ESFPs, ESFJs, ENFJs, etc). Also, it puts a smear on ENFPs as I know many ENFPs who do not need to strive to be in constant interaction and when they want interaction, they get it. Not because they are whiney. Not because they are manipulative. Not because they are passive-aggressive. They get it because people generally LIKE to hang around with an ENFP. Rarely will an ENFP find themselves in the situation were they cannot have interaction. And it doesn't have to be "new people and things".

"The dominant function of ENFP's (and their brothers the ENTP) is Extroverted Intuition, which makes them damn near psychic. :)"

That would be Ni (Extroverted Intuition) that is "damn near psychic". Ne is quite different.

"ENFP's love to roll the dice and sometimes are quite stupid about it. Risk taking is thrill-seeking for ENFP's. While the ENTP is a risk taker, the ENTP will take a risk for gain — an ENFP does it for the pure thrill."

Once again, this can describe many other types (more specifically SP's in general). And even if this where true you are once again incorrect about the ENFP/ENTP risk taking business.

John Lennon was an INFP. Gandhi may have been an ENFP. Also to try to figure out any types musical tastes or use musical tastes to describe a type blurs a non-MBTI readers understanding of MBTI even more so. MBTI describes decision making, not behavior, interests, etc. Some things can be generally correct however to understand the system in it's truest sense you must understand that it is all about the decision making. Thats is why the J/P can make such a difference in types (ENFJ - Fe, NI, Se, Ti vs ENFP - Ne, Fi, Te, Si). The functions pivot around that J/P. Once this is understood you may delve deeper into what the system may imply. Otherwise, don't smudge the MBTI system more than it's already been smudged.