There are too many tests falling in this category which are just plain crap. However I think the Myers-Briggs test stands out from this pile of crap (eg. the daily bullshit of "what kind of animal would I like to be") since the authors have made serious effort to really measure something.

They may have made an effort, but they're not measuring what they think they're measuring.

In the first place, too many of their questions make unwarranted assumptions, and your answer can only mean anything if the assumption happens to hold true for you. This creates a lot of statistical noise.

Additionally, it's a self-evaluation; if you're going to do that, you might as well just ask the subject "Do you pay more attention to your thoughts or your feelings?" and have done. The answers are going to have more to do with the way people think of themselves than the way they actually are. And I can tell you for free that most people don't think of themselves the way they really are.

But perhaps the biggest problem is that the four continua they chose are highly arbitrary and wouldn't necessarily form a meaningful description of a person's personality even if the results for each continuum were totally accurate. They don't even attempt to measure the stuff that really shapes the way a person thinks, like whether he makes his decisions based on perceived outcome (teleological) or based on some criterion independent of likely outcome (deontological or cetera), whether he believes in per se truth (as opposed to relative truth), or whether he thinks in sounds (verbal/auditory), pictures (visual), abstract concepts, or some other form.

It is my considered opinion that Myers-Briggs is completely useless for any serious purpose.

So yeah, put me down as IDFC.

And yes, I've been given the test a couple of times. I don't remember what the results were, but I do remember that the whole thing was clearly very arbitrary. Am I an introvert, or an extrovert? I don't remember. I'm not really sure the question applies. I have zero anxiety about talking to strangers one-on-one or in small groups, will walk right up to anyone and say hello, have been known to ask personal questions within two minutes of meeting someone, don't at all mind speaking to a large group, even semi-formally (e.g., classroom setting), will willingly make a fool of myself onstage (e.g., clowning), HATE parties, spend almost all of my free time alone, have a small number of very close friends, have no difficulty saying long-term goodbyes even to the closest of them (including family; at age three I had no anxiety at all about spending two weeks away from my parents), live in my parents' basement (literally), and understand both dogs and computers better than I understand people. Does any of this matter, or set me apart from the rest of the population? Meh. None of that is really even an important part of who I am. Fundamentally, they're asking the wrong questions.