It is said that the fallacy was named after enemies of war literally poisoning wells of the opposer before a large battle in history.

Poisoning the Well

(Discrediting, Smear Tactics)

Definition:

a person who presents advance adverse information with the hope of discrediting their opposer and what their opposer has to say

The fallacy is flawed because it is not good sportsmanship to insult or belittle your opponent either in a war or a debate.

A person may use this fallacy to make themself seem like the better choice in either a debate or a fight. An example could be Trump and Clinton in the presidential debate as they talked down about each other and their political party in general.

One day, Princess Shelby was walking to town. While walking, she stumbled upon a injured pirate who needed her assistance.

"Help, help! I have fallen and I can't get up, fair lady!"

"Of course, kind sir! I am here to help!"

"Thank you, fair maiden! For your kindness, I shall warn you. There is a rabid dog coming down this way, you should really go back home! It is a terrible dog, and deserves terrible things."