It could be a factor, couldn't it? Scanners vary - my old one was dreadful with reds so in the end I ditched it, and have yet to replace it. I do think violets and magentas are - somewhat like deep reds - colors present in Fiction House books at certain points in the print run when the colors really 'pop'. It seems to me that FH's printers tried to eke out the colors - ie printed too many copies of the covers before re-inking the plates. So between re-inkings, the colors would gradually weaken in density. I notice that certain colors are used to add fine detail to, say, folds in clothing, but copies where that is present are far scarcer than those where that overlay is absent. But it's all complicated further by what happens to a given copy over time - storage, sunlight - and finally, the quality of a scan.
I've taken the Rockford copy and run it through a single filter in photoshop. I found the results rather surprising. [Warning - these images may damage your health!]
Here is what happens when the reds are tweaked: