OK, so the ghost's faces fade because they forget what they looked like, who they were etc. over time.
Didn't the Lady in the Lake ghost walk past a giant portrait of herself on the stairs every time she went into the house?
That’s SO true. In fact, it’s cracking me up now that you’ve mentioned it.
shareOver hundreds of years sleeping, waking, walking she forgot what they are actually doing there so the portrait of herself was insignificant to her as she'd forgotten over time that the painting was of herself.
Her actions was of a far distant fragment of memory, it was something she simply did.