My model would not export some surfaces to Google Earth .kmz
Turned out that only certain colours were failing to export. They were all renamed colours, appearing in my "In Model" colour set.
I tried updating to Sketchup 8.0.11752, and renaming the colours again, but it didn't work. Tried "fixing" the problem in the model-info menu but that didn't work.
Thanks to your hint, I edited the RBG by one notch and it fixed the problem. Don't know why or how my colours got corrupted.