I don't really know anything about the 3DS file structure, but I would guess that as SU itself has no other material properties than colour and texture, the exporter would set all the other required values to something considered as a default. Most users export 3DS in order to render the model in some external rendering application by adding lights and other features not available in SU. In the applications I have used, the ambient property of a material, makes it glow quite unrealistically, so I would have had to turn it off. I am not even sure that the property is set by SU. If it is optional, the problem might even be with your receiving application or its settings, if it adds a black ambient "channel" if your 3DS file has none.
Just blundering guesses
Anssi