Some years back, my girlfriend moved with her then-husband (yes, they are now divorced) back to Santa Clara County after having lived in Sacramento. They rented a two-bedroom/two bathroom apartment in a modern apartment complex. On the whole, it was a nice place, but there was one thing that always bothered the couple: one of the bathrooms didn't feel quite right. The couple rarely used that bathroom, guests avoided it and used the other bathroom, the cats wouldn't go into the room, and whenever anyone would take a shower in that bathroom they would report feeling on-edge the entire time, as if they were expecting someone or something to attack them. One time, a cat was locked into the bathroom while the rest of the apartment was being cleaned, and when it was let out, the cat attcked my girlfriend, something that it never did when locked in the other bathroom.
Commentary: I have come across a number of similar stories - a room that simply doesn't feel right, nothing is ever sean or heard, no truly weird or unexplainable events occur, but the room just feels wrong, and everyone seems to notice it and react to it whether they have been told about it or not.
I am fascinated by this type of story for a simple reason. While some of these stories have pretty obvious explanations (if you tell everyone that a particular room is creepy, the power of suggestion can go along way), others don't. To be certain, there is not shortage of possible explanations, running the gamut from the reasonable to the absurd, but I have yet to see one that clinches the deal. In other words, this is one of those places where a clear explanation as to what is really going on is completely lacking, and that makes it interesting.
I have little else to say, but this sort of story, where I don't yet have an explanation, is one of the things that keeps me interested in ghost stories.
Sources: Personal Account