Yes, it is a challenge, but it is done occasionally. It involves very detailed textures, subtle bumpmapping and careful use of the spec files that FSX supports, but these are hardly ever implemented.
Look at the latest A2A P-47, that has all the shine and shape that I would like to see, but then Martin Catney, the man who designs their textures is a genius in my opinion...

John Terrell did a great job on his P-51B as well I think:
