I am currently in a group that I've noticed don't ask much about the physical descriptions of the NPCS or enemies, I plan to GM somewhat soon i've decided to make a somewhat standard dungeon:
The PCs will enter the dungeon to search for the local princess with a NPC provided by the King,a low leveled(2-3) swordsman to increase survivalability for a group of 4 Level 1 PCs. The dungeon is a small military base inside a cave with some Soldiers with spears, crossbows, and battle axes aided by Adepts who'll do 1 Cure light wounds or Burning Hands who then run and use Ghost Sound to alert other soldiers. Then comes the Big Boss fight with the Strong Half-Orc,his Cleric buddy who teaches the younglings and guess who? The Princess, who just happens to like their Gene Simmons deity worshiping cult.
But then I got an idea. Wouldn't be interesting if there was some deception in the group? Wouldn't be awesome if the King's swordsman was a skin stealer, whose goal is to steal the Princess's skin and murder the king? How should I play that out?
*Edit, I forgot to add that I've read that the Skin Stealer steals the skin, height,weight and voice of the victim, but it didn't specify anything about the eyes. And I planned the Princess and the Skin stealer didn't have the same colored eyes.