My 8" used to be white, I repainted it white when I remade it but couldnt keep both eye's open when observing (less strain on eyes, makes a longer night) so I decided to change the colour to Black.
http://members.optusnet.com.au/astro.../scope_obs.jpg - white scope
http://www.theastroweb.com/astronomy.../scopedome.jpg - black scope