The most obvious reason that they couldn't believe their eyes was the way that the women were reacting towards Tianlong Yun's and Sonia's mixed juices.
But the biggest reason behind that was that no matter how much they tried to have a look, none of them was able to look at Sonia's body.
It felt like she was some kind of illusory ghost as their eyes were unable to make sense of her naked body.
As people with some strength and power Master Aldea, and the other guy certainly had some knowledge of supernatural existing, but it was only now that they were able to think they were witnessing it.
Since Sonia was one of his true women there was no way that Tianlong Yun would even allow those guys to have a look at her body, as it belonged only to him.
Dragons were greedy creatures for treasures, and shiny things by blood, but Tianlong Yun had been from birth greedy for women and the sense of warmth coming from their bodies.