Speaking to one’s dismissal and judgment of a person or thing. This was a realistic portrayal of being happy to make tracks in an opposite direction from someplace: shaking the residue off implied one wanted for no relationship with the spot to stick to one’s individual. “And whosoever shall not receive you, nor hear your words, when ye depart out of that house or city, shake off the dust of your feet.” Matthew 10:14 KJV