If, for instance, you were GMing and you described a foe in a way that screamed particularly deadly and capable then when the PCs defeat that foe they are going to think their characters are deadly and capable even if the foe were at exactly their challenge rating or level. After all the PCs don't usually know the monster's or NPCs stats now do they?
The players, however, are going to notice patterns, and they have more than just your verbal description to go on. They'll notice how much damage they take, and how ugly the situation gets before they win. So, if you regularly give that kind of description, but the foes go down easily without doing much harm, they players will learn to not trust your descriptions.
A similar principle works in movies and television. When Aragon fights the Urak-hai at the end of Fellowship that felt like a tough battle with a capable foe that Aragon barely survived. Mostly it's because the Urak looked intimidating and snarled a lot (and took a sword through the chest no problem, enemies who do that are always badass). The point is we don't know that the Urak was more powerful than Aragon but it sure looked that way.![]()
Yes, but that's in part because we didn't see Aragorn's hit point total through the combat.
