Basically if you have say 90 SS and then use a bloodwood spirit to boost it to GM you can't see ghosts unless they are in war mode. I was under the impression that if you used items to have 100 points in a skill it should work just as well as if you had 100 real points in a skill.
EDIT: You also cannot understand what ghosts are saying.
EDIT: You also cannot understand what ghosts are saying.