Xavier Remington 
As far as television and movies are concerned, all non-corporeal beings seem to have a firm footing on the ground they walk upon. Despite this, they can walk through walls and pass through all other solid matter on our three-dimensional plane. This seems to be the case whether they’re ghosts, spirits, poltergeists, or demons. We even have people from Parallel Universes or simply the sub-atomic level altered who are not totally phased into our reality that exhibit this behavior.
In reality, ghosts and other beings lacking complete physicality in our world tend to appear to float about most of the time. They don’t necessarily always float above the floor all the way. Sometimes their legs appear to be cut off. Ghosts are often extremely confused spirits who will inadvertently gain traction on a surface while remembering their life as a live human. When ghosts and other non-corporeal beings are intelligent with a clear mind then they can learn to phase parts of themselves into our reality so they can indeed walk upon a floor or touch objects. This includes violently launching them across a room in a rage.
In addition, ghosts and other entities not of pure evil can walk upon the hallowed grounds of graveyards, churches, etc. The sites of their death are also considered hallowed ground and there their power is strongest. The soles of their feet are horizontally solid upon surfaces for brief periods of time as their metaphysical energy interacts with the enchanted energy given off by the hallowed surface.
