Some enemies are able to see through disguises and can be alerted if the player enters their vision, and all enemies can be alerted to suspicious behaviour which includes picking the lock of a door or looking through a door's keyhole, being in certain stances, or having certain weapons visible.
Adversaries can detect disguises and become aware when the player enters their visual range. Any enemy can be alerted to suspicious actions like unlocking a door, peering through a keyhole, maintaining certain stances, or displaying visible weapons.