The Monkey King got an eye disease in the accident of 7749 days in the Eight Diagrams Furnace of Taishang Laojun. He is afraid of smoke and fire. Without magic, he can't see through this monster. The reason why he can see the auspicious clouds and evil spirits on Tang Priest's head depends on the Monkey King's own way, which Tang Priest, Bajie and Friar Sand can't do.
Therefore, Wukong can often see at a glance whether he is a monster, a fairy or an ordinary person standing in front of him. Only once did I miss my eyes, and that was when Niu Wangmo turned into a pig and cheated the banana fan away. Later, Wukong himself admitted that the reason for his failure was that he didn't plan ahead after his success and didn't notice the clouds, so he took the road of Niu Wangmo.
Functional analysis:
Fire eyes and golden eyes function one: Fire eyes and golden eyes can know monsters. This should be clear to everyone. In Monkey King Thrice Defeats the Skeleton Demon's The Journey to the West, this function of the critical eye is fully displayed. In addition, I have to remind you that critical eyes can see not only monsters, but also needs. For example, the Monkey King can see the demand in the house changed by monsters. It is the golden eye that has this function, so the Monkey King's mantra in many film and television dramas is: "There is a demon ~"
Fire eye and golden eye function 2: Fire eye and golden eye have perspective function. This function is even more remarkable. According to the original book, when the Tang Priest and his disciples passed through Zhu Ziguo, a list was posted under the tower. Because the list was presented by the emperor himself, many people read it. The Tang Priest asked Wukong to read the list, but the Monkey King was short and couldn't use magic in downtown, so all the Monkey King saw was heads. Then the Monkey King flashed his eyes and saw the list.