I recently owned a 3000 mile '79 TATA and that paint looked exactly the same under the rear deck as it did in the nooks of the fenders and door jams and behind the carpet as it did on the top of the hood and trunk deck. Based on some of the logic in this thread I just have to ask myself 'I wonder what color it was originally?'
Earlier this spring there was a 14K mile unrestored '74 Firebird Formula Gulfmist blue for sale that I had the privilege of looking over prior to it's sale, and I can again say that paint was unchecked, not faded, and as best as I could tell had not changed color.
IMHO, and with all due respect, to begrudge a guy who goes to the trouble to try to replicate a color as close to original as any logical person could think of a way to do it, by saying he is just 'guessing', is at best illogical. Instead, I'd think anyone that chooses to use OEM, or any other color in which the person doesn't know the history or reasoning behind the color mix is.....'guessing'.
Bentwheelbob and RAIII, what are you going to use as the datum in the double blind to match the color shades from the various manufacturers to?