Huh. You're right, I never thought about it that way. I had to look it up and apperently there are multiple theories that the reason ufo photos are always terrible quality is that there's some kind of terrible-photo-force-field around them. Great stuff!
The truth is that when we see photos of Nug the mind-bending eldrich horror of the sight disturbs the vision part of our brain. The photos are all perfectly clear, but simply too terrible for our tiny minds to ever percieve.