Agreed.
There should be a Build Up of some sort.
But currently, I must admit. Since we all know what SCP-106 looks like, It may not have such an effect.
If there is ever a chance that is Model is updated [ And loses the Chocolate Texture since I am sure SCP-106 is not edible ], Then maybe It would work.
Perhaps finding Corrosion Stains, Corpses covered in that Black Mucus, Two Eyes staring at you from the Darkness of the Tunnels and disappearing when you approach.
I can easily imagine the Player taking the Lift down to the Maintainance Tunnels, Only to have the Lift come to a stop.
A black Stain appears on the Wall opposite the Lift Door as that Eerie sound plays. SCP-106 slowly emerges and looks around slightly before focusing on the Player. He laughs as he disappears back into the Wall.
The Lift opens and the Chase Music starts. You've got barely a few seconds before he rises from the Ground.
SCP-106 is now on the hunt. And you are his target.