I just got back from Best Buy where I was comparing the feel of the 70D w/18-135 with a Rebel w/18-55. No filters.
While looking through the viewfinder of the 70D, everything was noticeably tinted - sort of a light serpia. I didn't try LV. The view through the Rebel was neutral.
The clerk took a couple of pics and the color looked right on the rear LCD, but through the viewfinder the color was distinct and disturbing.
I know these display cameras take a beating, but I wonder what could be wrong.
I found this answer for someone who had a tint in the viewfinder of their 7D,
"The 7D uses an active LCD screen that you are looking through when using the viewfinder. Maybe yours has a problem?"
Could this be the case with this 70D