The Vedas say, Yad Bhavam Tad Bhavati ( you become whatever you think). When you constantly think of others faults, that evil enters you. How ? When you have a camera in your hand, to whichever direction you turn and click, that is the picture you will capture.
 

Your Body is like a Camera
Your Vision is the Lens,
Your Heart is the Film &
Your Thoughts form the Scene.
Your Intellect is the Shutter.

With your Intellect, absorb only those impressions into your heart which are spiritual. If your thinking is bad, it gets imprinted on your heart.
So, do notentertain bad thoughts.