Ok, so I take a model in Sketchup, export it as Collada .dae file, and import that into Blender. The model is a solid, white on the outside, and red on the inside so I can tell which face I am looking at.
It imports into Blender like this:
As you can see, all the normals appear to have been reversed. Through much research and experimentation, I figured out to clean up the model, I select each part, edit it, remove duplicate vertices.
Which seems to fix it, except, problem is, I seem to be getting some faces that it chose the improperly flipped version of the face when it removed the duplicates.
As you can see, the normals for that item are flipped as the lighting is backwards. Normalizing the ... normals does this:
Any idea how I can fix this? Or is the only solution to make sure the inside and outside of every face is the same color?