I have never seen a ghost .... wait a minute! In the days before digital tv, my television's antenna sometimes gave rise to ghosts due to multipath distortion of the tv signal. Is that what you are asking about?
I used to see ghosts ALL the time, until I finally got Cable TV.
I saw and heard a ghost, i.e. my deceased sister.
i don't see the air that i breath, but i know it's there