Rav Bunim of Peshischa zy”a explains that Pharaoh obviously knew that tzadikim existed who possessed the ruach of Hashem. However, he thought that they were all recluses who served Him in solitude, with no connection to the outside world. He believed that one could only reach this level if he removed himself from all earthly matters. He now saw that Yosef was such a tzadik, despite having served as the manager of the house of Potiphar. He oversaw the entire household and fields, and was fluent in 70 languages, and also was of fine appearance, yet he still had the holy spirit of Hashem within him.
This is something Pharaoh had never seen. Thus, he exclaimed that he never knew that a man “like this” could still be a tzadik.
