It's not what it means, but it is something they are capable of. They can be charming, and they can be horrible. They decide what they are going to be like, to fit into an overall selfish strategy. If being shy is an advantage, they will become that. If being confident is advantage, they will become that. They can gain your trust, then flip when it is an advantage to do so.

In these tests, they know what to say, what to do, to give a certain impression. These tests can't catch them, because they are not honest, and lack integrity(No consistent values, only ones that benefit them).

More specifically, the psychopaths that you're likely to run into in a tech company fall into this class.

There are certainly psychopaths who are hopeless at concealing the fact. These are typically the less smart ones, so you wouldn't meet them; they are more likely to be in and out of prison than your office.

There are also psychopaths who are just about perfect at pretending not to be, and have no intention of ever doing otherwise. You can work with one of those for decades, and never notice a thing unless something extreme enough to make 'acting normal' seem a long-term liability happens.