The description for Ghouls in the SR 4 rules states that they are dual-natured and blind.
I am interpreting that as they perceive things using astral sight at all times. Assuming that is correct, if a magician uses Masking or Extended Masking successfully with regards to the ghouls, is he in effect invisible to them or do they see his physical form as with a mundane aura or whatever altered aura he selects within the parameters of the description of 'masking'.
I guess I'm asking if the magician can use masking to just fade into the background and completely surpress his aura so he is effectivley invisible to them.