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).