Answer:
"The Nun's Priest's Tale" criticizes fawning, showing that fawning is not to be trusted. This goes completely against heroic narratives, where heroes were very flattered and liked it.
Explanation:
In heroic stories, like Beowulf, flattery is constant. That's because a hero who promotes the good of society through his strength and masculinity, must be pampered, praised, loved and presented, just as happened to Beowulf after he liberated the people from the monster Grendel.
However, "The Nun's Priest's Tale" ridicules all this flattery. In this story, the hero is not flattered, but flattered by the villain, who is so self-confident that he concentrates on his prey and ends up losing it. With that this story shows that flattery makes the individual lose focus and thus lose battles. Who flatters the hero does not want him to feel good, but wants to distract and win him.