I saw a commercial for PS and it could have been the episode that you mentioned.  If so, it showed scratches on someones back.  I did not see the episode but I do have a couple of observations just from seeing the picture.

Whenever you see the mysterious, ghostly scratches on the back, look at the angle of the scratches.  Quite typically, they begin in the middle of the back and taper off to the side of the body (away from the spine).  Pretty easy explanation for this.  Place your own hand on your back.  Pretend to scratch your own back while angling your hand so it could apply enough pressure to produce scratch marks.  What was your result?  Your hand was in the middle of your back and your pretend scratches tapered off to the side of your body?  Yeah…not rocket science.

Now we have a person into self-mutilation.  Maybe…just maybe…this isn't someone that you should shove the hot lights and cameras into their face.  You want to help them?  Great.  Get highly trained professionals in there and pick up the tab.  No ghost investigations, no exorcisms, no nonsense.  Just show some compassion for another "living" human being that obviously needs some help.  This is essentially why I despise PS.  The other shows just talk to the dark and mis-use their equipment.  This show…they hurt people under the guise of "helping."  (Look at other threads in this forums for evidence of this)

I saw just a bit of a show last night.  A family had recently suffered a suicide of a teen.  Her sister and perhaps other members of the family were claiming paranormal activity.  In swoops PS to "help."  Can you imagine that?  A couple months after the suicide, they ride in with their cameras.  Wow.  I changed the channel and sat there just swearing and mumbling.  Later, I turned back and they had a Priest "blessing" the house…at 3:00am…*sighs*

It pains me to no end that this show is still on…