What does an oracle with clouded vision see when someone casts, for example, silent image?
Do they see:
1) Nothing. It doesn't really exist, so their extra-sensory darkvision wouldn't pick it up.
2) Exactly what the caster wants them to see, ignoring the curse and making it an obvious illusion. (The spell says "This spell creates the visual illusion of an object, creature, or force, as visualized by [the caster].")
3) A 'cloudy' version of the illusion, requiring them to interact with it to get a save, as normal.
I'm reasonably sure the intent is option 3, but the other two options would be very interesting from a GM and player perspective.