Spraypainting creations, and saving with Creative Mode causes the saved object to load weird.
I found this odd bug a while ago.
When I spray painted the rock cube made in Creative, saved it, and spawn it, it comes out all weird.
From what I can assume of this bug, it causes the spawned creation to be all black on the areas that were spray painted, and for the spray painted area' material type to get mutated (presumably based on certain colors and shades), which caused the cube to be presumably part wood, rock (original material), and metal.