Does the room 1408 only hurt and kill Guilty people?
The room 1408 conjures a fake Olin to tell Enslin that "You shatter peoples hopes for an afterlife with your books. People want to believe in ghosts because it gives them hope, and you take that away from them" (paraphrased). So in that way, the room is telling Enslin that he deserves to be punished.
Im rewatching the movie today, but It'll be hard to know if the people it killed were guilty of something.
It would explain why the room was rented out for so long before a manager (Olin) made the room unavailable. Think about it, if every single person that checks into 1408 dies, the staff wouldnt wait long before making the room unavailable to the public. But if the deaths in 1408 was seemingly random and sporadic then it wouldnt cause alarm for some time.
This makes sense if the room only hurts guilty people, and leaves innocent people alone.