When I purchased it secondhand about two years ago the main mirror was pretty dusty, I was also struggling with some collimation issues. So I decided to pull it down, clean the mirror and check the mirror support. A friend is a professional automotive spray painter and offered to spray it for me while the 'scope was in a million bits.
This is not the first GSO RC I've owned, and I was bored with the whole "black-on-black" thing. We were going to go with a cheerful candy apple red, but I thought white was more professional and scientific looking.
To be concise, the reason it is white is because of dust and a short attention span
The mirrors are both perfect with no blemishes of any kind, though like all RCs, just a little dusty.