Right in the beginning of Shulchan Aruch we see this idea of "Ruach Rah". In regards to washing ones hands and all that comes before that -- not walking more than 4 amos without washing one's hands, ...
If one washes netilays yadaim in the morning and thus eliminates their ruach ra'ah and then someone who has not yet washed their hands touches you do you have to wash again?
What do Jews believe about ghosts and evil spirits? It seem to me that the Bible gives clear definition about the fact that they are real. What do Jews believe about this?
Some Posekim write (Yalkut Yosef Hilchot Mayim Aharonim and Mishna Berura 181, 4 and IIRC the Magen Avraham) that Mayim Aharonim has Ruah Ra'a and that once someone used the water for Mayim Aharonim ...