The rules regarding ghosting have been made a bit more clear.
In short:
Ghosting: using a character that’s naked/dead and not used as a character that you usually play with to scout dungeons or stand at an entrance and wait for other people to arrive.
Not ghosting: Scouting or standing in front of a dungeon hiding using a geared character that you play with normally.
Good practice would be to detect any hidden characters before entering a dungeon. That way you will reduce the chance for any surprises.