Alternate Character Interpretation: In-universe. The reindeer have very different views from ponies (and viewers/readers) on the Mane Six. The reindeer believe the Mane Six are Celestia's personal wetworks squad, a team of hand-picked elite troubleshooters led by "the most powerful and evil sorceress in the world", who take care of all major unrest in Equestria, and let Celestia be the benevolent ruler of a perfect little sugar bowl as far as everyone else is concerned.
Uncanny Valley: Invoked within the story. Spike finds nidhoggs disgusting because they look very similar to dragons, but clearly aren't dragons.