I have looked at most of the pictures, and I must say that these "hidden demonic faces" are dubious at best. I really think that this is grasping at straws. I have been able to see similar images in clouds and in pictures of smoke.
Just for fun, I decided to pick up a National Geographic magazine off of my book shelf right now. Within just 2 minutes of glancing at various photos, I was able to pick out about 3 skulls, and 2 demonic faces. It wasn't hard at all. I challenge any of you reading this post to try it too, and count how many faces and skulls you can find within various pictures.
Whenever looking at photos of images that contain a lot of random and chaotic shadows, and textures, it is always easy for the human eye to pick up patterns. Faces can always be found.
I'm not saying that the people who create these websites are dishonest or deceitful. I just think that they may be a little overzealous.
Just my own personal opinion.