I do recommend a mod like Fallout Character Overhaul that offers better and more interesting ghoul player models though. Although this actually isn't what flags the player as a ghoul.
This is mainly done through heavily editing and splicing the dialogue found in the base game. No longer will they be recognized as a human by the other denizens of the wasteland. Gameplay and dialogue has been changed to fit the Courier's ghoulish nature.
A mod that actually lets you play as a ghoul in an immersive and lore friendly way. This mod intends to feature something that even after seven years of modding has yet to been appropriately created.