I guess this is going nowhere unless you grab your friend's 5d2 and take the exact same shots with the same aperture/iso on the 70-300L and 70-200L.
What? My friend doesn't have a 5DMKII - he has some kind of Rebel.
What I said was I put it on my
5D MKII, with my color corrections and workflow, and tried to eliminate variables. I still get washed out pictures. Further I've seen shots taken with the lens online, and sure with all the variables of monitors, JPGs, workflows, etc, they still look washed - generally. I have seen a few that look OK.
Any shot taken with my 70-200 or 24-105 has wonderful colors, but I can't do the same with the 70-300 in the time I've taken with it. Has anybody else seen this?