The accuracy of the WOFF skins is no more or no less reliable as what you will find on a good modeling sight or book. Even on a well documented plane, where the colors are known, the exact shade is just a best guess. And, of course, you usually don;t see the whole aircraft, so you have no clue as to how the topside or underside looked. Was there a letter or number on the underside for additional identification? What color is the marking on the fuselage, it looks white or black, but is it? Lots of guesses to make, even if they're educated guesses.
What plane, in particular, are you looking at? Maybe someone knows where those colors or markings came from. I give the sources and reasons behind the modifications I make in the ReadMe word file that accompanies the Mods, but that's not the case with the WOFF skin pack. There were lots of people working on that massive project but maybe someone whose still around remembers..
Jerbear