As a perception filter doesn't actually exist, we can't really say how it works.
She was human the hole time, so it never stopped working. If you can perceive clothes that don't exist, perceive them moving as she walks, there's surely no reaon you can't perceive them being removed. The fact they don't exist isn't relevant - I imagine when the device stopped working, the clothes around her would 'disappear'.We saw the effect of the perception filter when disabled, the creature wore no clothes. So its not a matter of perceiving that clothes are being removed, its a matter that a creature not wearing any clothes cannot stop, stand still and then carefully remove clothes. You cant take off something that doesnt exist
)Surely not, as the clothes are not real. Yet when she removed them and threw them on the floor they remained on the floor. At that point they are not in contact with her so how can there physically be an item of clothing on the floor when there is no physical piece of clothing to discard and drop onto the floor. I am guessing that the reason why the clothing appears to be on her is that the perception filter effects her physical body to make it appear like something else, the fact that she has to wear the perception filter would suggest that it is required to be in contact with the wearer in order to work, so a "holographic" piece of clothing, when no longer in contact with the perception filter wearer, you would think should disappear. Much as holograms on star treks holodeck disappear when leaving the holodeck (although having said that there was also the episode of star trek where a snowball was thrown off the holodeck and hit someone, which it shouldnt have done as it should have ceased to exist when it left the holodeck of course
Then again, as I say, sci-fi has the advantage that everything can be explained.
Maybe it was that not only did she have a perception filter, but she also had biomorphic abilities and could generate physical items from hairs on her carapace which she then discarded.
I guess thats the beauty of sci-fi, we can explain absolutely anything with some excuse or another
Like last nights part where they set up so much around the church in around 3 minutes, we can explain that by saying it was because the Tardis was nearby and was emitting a time displacement aura which slowed the passage of time without slowing the physical movement of objects within that aura, thus allowing them to set up in the short space of time.
But it was specifically explained as affecting the mind. But the mind couldn't block out the dangerours/threatening part, hence the vampire teeth.
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