Its true. My Jeep never had a hood liner and the paint on the hood isnt in as good of shape compared to the rest of the paint due to the heat, its alot lighter and some of the warmer spots really show.
The flat black spray paint trick will also produce a nice, fresh looking mat. I did a couple years ago, and only came up with the custom idea this past winter.
Flat black is the key and it will look better than a new mat.
~Darren