Maybe these negative traits were a local phenomena only. But as they journeyed all over Earth, to both densely populated and sparsely populated areas, and among different-looking Earthlings of all kinds, the aliens noticed that the behavior was the same. The aliens' report was not very enthusiastic about Earth or Earthlings. So they returned home, frustrated. There are things we do that God would never do, and things we don't do that God would do.
Sin simply means to miss the mark.
You might be a little closer to center than someone else, but all of us miss the mark. And if someone were to judge God by first judging us, God would not be considered a very nice fellow. Quite possibly no one would want to know Him at all. However, even as messed up as we are, God wants to know us. He wants to be in relationship with us.