Btw, I just reread the book of unfinished stories that Sauron is only able to corrupt people/elves through other objects, like the might rings or Palantirs. (He could seduce people in his "beautiful" form, but he's not able to use it anymore.) Palantir's were those big balls used to communicate and search in middle earth. Saruman, Minastiritith and Sauran had one.
Saruman didnt have right to use the Palantir, because he wasnt a king, and this is exactly why he was easily corrupted by the Dark lord, but the Keeper of Minas tiritith (Forgot his name) wasnt corrupted under the Dark lord's will, but Sauron was able to kill his will of life and weaken him (this is why he tries to end his and his own life in the third part of the book, and he's not willing to battle because he "knows" he's going to fail.
🙂