Shameless self-promotion
I think someone wrote on my talk page once that MBTI is the thinking man's astrology. I-E is the only scale with any sort of validity. But I've always found this profile kind of spookily accurate. Never took an IQ test, though.
I get bored with IQ tests. But I see what you mean with "thinking man's astrology", but in the end it's just trying to put neat little rings around complicated clusters and saying "ABRACADABRA!! This is now a Real Thing!!" Hence why you're stuck unable to answer "yes" or "no" to all these questions because you're kinda both. I always feel wrong answering "I feel introverted and uncomfortable around strangers" AND "I feel like being the centre of the party" to these things, because they're blatantly contradictory, but it's true.
The Mill quote in Gould's review is timely: "The tendency has always been strong to believe that whatever received a name must be an entity or being, having an independent existence of its own, and if no real entity answering to the name could be found, men did not for that reason suppose that none existed, but imagined that it was something particularly abstruse and mysterious."