I don't know about ESB and ROTJ, but I can tell you that in any version of SW the colors are inconsistent, and they've been confirmed to have been like that on some original prints as well.

Here are some examples from SW. Since GOUT-SW is so desaturated I'm using my script that boosts the colors so it's easier to see:

1 - Top shot has more red, especially visible in the whites on R2.

2 - Bottom shot has less yellow / more blue in it.

3 - Probably the most visible inconsistence in the movie, the bottom shot is pink tinted.