In classic D&D, elves have the following abilities:
-Detection of hidden doors
-Immunity to ghoul paralysis
-Friendship with animals
So let's imagine orcs as things which can:
-Magically conceal any doorway or entrance
-Cause paralysis with a touch
-Dispel magical spells cast by others
-Destroy natural life, maybe by draining its essence in their surroundings?
This gives orcs more of a feeling of a creature from a fairy tale, but not one that is entirely displeasing. It certainly makes them seem more dangerous.