Because the Demon Emperor Xue Tian has one foot in the Peak stage of the Fifth Heaven of Nirvana Realm.
Thus, his spying methods are completely undetectable to Su Yue and others, unless someone possesses the same or surpassing power as Xue Tian, only then can they discover Xue Tian's spying.
Originally, Xue Tian was very interested in Ye Chenfeng and even speculated whether Ye Chenfeng could become his opponent.
However, after confirming Ye Chenfeng as a Fifth-Rank Alchemist and a Sixth-Rank Artifact Refiner, Xue Tian's thoughts completely changed. He needed a powerful alchemist and artifact refiner by his side to have others from the sect participate in recruiting Ye Chenfeng, which was more than enough for Xue Tian.
The Demon Emperor Xue Tian is a proud person, and in his view, there is no one in the Earth Profound Realm worthy of his personal attempt to win over.
As the Demon Emperor Xue Tian and the ten Demon Generals left the Liutian Sect.
...
The Earth Profound Realm.
