1. Hide and Seek: Cute kids, I like how you incorporate the chinese essence but maybe you should give a little bit more description on the prayer room so we can picture it in our heads. Potential to end off scarier such as making the ghost appear in front of Kris or Sehun for a longer period of time; ghost has attached himself to Sehun for example.
2. The princess and the "pea": This was good because the devil staring back at the end was quite creepy but you know what could have spooked your readers to death? A picture. 
3. The Creaky Window and the Door: This story was a tad bit confusing especially towards the end cause it felt like you were repeating the story to before Seohyun went into her room and then I think about it again it didn't seem so. 
4. Mirror, mirror, on the wall: Yes the mirror was creepy but I felt the saseang fan lead up was a bit irrelevant and unncessary. You could have written it from a second/third point of view
5. The Last Bus: This was quite good. Creepy. *thumbs up*
6. Selfie: There wasn't a punchline; it looks like a happy ending to me and not scary
7. Lizard's Treat: Nice horrifying description of the "monster" but once again there wasn't a and my question is; so was his wife like the mother of lizards? Why did the old man kill lizards then? Shouldnt they be like his babies? It seemed to be the old man was feeding lizards to his wife which would not make lizards part of her final attack
8. Sooyoung (part one): Good imagination on this story! Hot and sadistic. But you might want to add more bulk into what happened to Sooyoung; give some hints into some form of possession like how she suddenly became lifeless and not herself anymore; unable to control her body etc 
9. Toilet antics: Sorry but I didn't feel a necessity for this chapter; could have made the saseang scarred and imagine things or get haunted haha
10. Sooyoung (part two): Same as the above; I don't feel the good connection. When I started reading it it seemed interesting cause I was guessing some reincarnation story but in that case Sooyoung should have felt the feeling of being the victim not a bystander. Couldn't catch the gist of this story sorry
11. Blind: I honestly cant decide if I like or dislike this story. Firstly it was confusing because your first part made it sound like Taeyeon had already taken off her contacts due to mother's nagging. Also, contacts feel nothing like an eyeball; I thought she had picked up Yoona's contact lens instead. It could have been made creepy if Taeyeon just ran her hands around and grabbed the eyeball and screamed; look up and see Yoona's face staring back at the mirror without an eye. That would have been freaky ;-)

Hope you find these pointers helpful ;-)