They were impressive either way. Some of the late high-horsepower power came from the factory in black, even before PC paint.
We didn’t get many of the big PRR Alcos as far east as the NEC, but I can still close my eyes and see and hear one of the C636s hammering through Trenton station, exhaust sharp enough to hurt the ears. Perhaps no more traction horsepower than everyone’s SD45, but it had lots more presence and charisma. And part of that impression was it being dirty, dull black, an industrial machine that was all business.
As, I think, did the various SD90s (and it fully survived in the ACUs). They didn’t have the battered-boxer phiz of the M-2s, but made up for it with presence, much like the RSD7s/15s and the bigger Baldwin in first-generation power, what DPM liked to call ‘honorary steam locomotives’.
I only started appreciating the original BN scheme, the one adopted-not the experimental scheme the CB&Q had on some units, until they started changing it. I never liked the tiger stripe or white face schemes.
I haven’t seen all the heritage schemes from all the railroads that have done them, but some are freight schemes. Even if passenger schemes, it’s still better than UP’s hodge-podge style of heritage paint. Often combining the colors of various schemes the predecessors used. Their only scheme that best looks like one used by a predecessor is the CNW unit.
I googled them and also found one from 11 years ago repainted in the jade green. It’s interesting to see because I know model train companies have done foobie paint schemes like that over the years like back in the day Tyco had a Penn Central F7 painted in jade green with the red “P” logo. As far as I can see while the real Penn Central did indeed have F7s they were all painted in black.