I've contemplated creepy recently, and think creepy = unnatural. The mind knows something is not normal or natural and instantly has a little revulsion, which we call creepy. It is probably a hardwiring in the brain that unnatural or slightly off means "genetic problem, do not mate". Robots that look humanoid but are not quite right. People who have a facial characteristic that makes them different from the norm. Shades of skin like "sickly green" or "ghostly translucent white". Things that have one thing out of proportion. The hallways and rooms in "The Shining" were so large that they created a creepy atmosphere.
Creepiness does have a place in our world. I do enjoy having things around that are creepy, watching creepy movies, and even the occasional creepy attitudes of a friend or coworker. It gives you a feeling. Not everything in life can be sanitized and removed of all painful or bad emotions. So many people are afraid of pain when denying yourself those emotions and feelings might be the worst pain you can inflict. Don't just go numb.