I was actually talking about almost the exact subject with another member on discord the other night. Indeed, it is a skill that some people are naturally better at than others, and there is also a heavy degree of learnability with it too. It also doesn't make the person any better or worse because skills in a vacuum are meaningless (well, more or less). What matter is what you do with them.
At the risk of sounding egotistical, I'll say that I have an excellent judge of character, and can sniff out bad eggs very quickly with seemingly little information in large part because I absorb this stuff naturally. Family members have come to me for "reads" of people even when I was a child. I use it everywhere, but it's come in very handy at work, and I recently learned that my manager hired me in large part because she sensed I was very good with that sort of thing (and being good at it is essential for my job). To get a read of someone, you need to take in information from all angles and not just read them for what they are, but how they interact with other elements. Such as there being discongruency with vocal tone and body language.
The quiz though is geared mostly towards "learned" things you could pick up on in a coursework on this sort of thing. I'm quite certain there are business firms that offer training seminars on this sorts of thing, and it would be backed at least in part by some research. If you follow that stuff too rigidly, it's liable to not be terribly helpful. Honestly, I think testing someone ability to understand non-verbal communication is dreadfully difficult. Too many variables, and you can't re-create all of the stuff that people come to rely on in the real world.