I'm still scratching my head at the idea that the whole of humankind can be shoe-horned into 16 personality types, regardless of culture. That's some A-grade deterministic codswallop there.
I agree. And every time I've done the test, I've got different results. Results vary depending on my mood. Plus, if I ever had to do this for a job interview, it would be very, very easy to find out what qualities they were looking for and answer the questions accordingly. I've also been sorted into all four Hogwarts houses on separate occasions in various online tests. Pottermore sorted me into Griffindor, and that's the definitive one seeing as JK Rowling wrote it, but on another online test that uses the same questions and method as the Pottermore one, but gives you a percentage for each house instead of just sorting you into one, my percentage for Griffindor, Slytherin and Ravenclaw were incredibly close, just a couple of percentage points between the three. (And I'm kind and loyal like Hufflepuffs too.)
When you break the Hogwarts houses down into subcategories, e.g. if someone's a Slither-claw (mix of Slytherin and Ravenclaw) you can end up with just as many categories as the Myers Briggs test. And it's got just as much scientific validity (i.e. not much). You'd probably get just as good results by asking someone outright how they see themselves in relation to the different categories. People generally already know if they like parties or are details orientated or whatever. Someone who hates interacting with large groups of people all day long probably isn't going to apply for jobs that require them to interact with large groups of people all day long to begin with.
I love all the personality tests though. They are great fun and I especially love the barmy ones. Like "what colour is your guardian angel's aura" and stuff like that. I just like seeing what results they give me. And they're even better if you use them for developing characters. I'd recommend that as an exercise for anyone who's struggling with developing a particular character - go on Playbuzz and answer a few personality tests on behalf of this character. You'll have fun and develop your character at the same time. I sort all my characters into Hogwarts houses. And find out what Avengers character they are, who their guardian angel is, what Norse god they are like and all sorts. I do this for fun, even when I'm happy with their character development so far. It's quite hard to do this for my characters in stories I write set 40,000 years ago or earlier because their answers to questions relating to situations in the modern world would probably be "freak out and run away" because they're only familiar with technology from the middle palaeolithic and early upper palaeolithic eras, but it's still fun.