The horoscope reference implies the "reading" of people applies to everyone on some level, so the chance of someone saying "It got me dead on" is nearly 100%, as everyone CAN be negative, and CAN be positive, and CAN be outgoing, and CAN be introverts, ad nauseum. On some level, we all have these traits, just at different times or in different circumstances.
What I see as the trick of it is people are told "you exhibit these types" and they all do, at some point. Kind of like a fortune cookie, just more wordy. You tell someone they exhibit that trait, they will dig up some time in their lives when that trait was indeed exhibited. If everyone was given a reading at complete random, they would still see it as dead on, simply because many people are externally opposing their internal feelings in order to balance, so they meet opposing criteria at the same time. It's the human condition.
The second trick of it I see is these readings are presented all in a positive light, so people are brainwashed into thinking their reading means they are the good ones, and opposing traits would be bad. They are trained to
want to be the person in their reading, because the alternative is less desirable, which simply isn't the case, since ALL readings say you are great person. I'll bet my lunch there isn't a reading that says "You are likely a mass murderer and should be fired immediately". People wouldn't take the test if it meant they would be told they were an awful person and needed to change.
I figured the word "horoscope" covered all of that in a more succinct package, though
