Of course it's always best to get it right in the camera, but sometimes things are beyond your control (or like me you didn't know until it was too late).
I shot some live music video for some friends who also had another person shooting some video. I thought it would be fun to put the two shots together for a more interesting final product. The camera I was using was an older Sony D8 tape camcorder while the other one was a newer little thing that recorded to flash memory. I realized that white balance could be a problem but went ahead anyway. After spending quite a bit of time tweaking the color correction (in Vegas 6) I got it close but was left with one particularly annoying feature. Some of the blacks in my footage had a weird tinge of color to them while the other camera's blacks were black. I had discovered infrared contamination.
I was determined to make it better, and I think I succeeded. Here are the steps I used:
1. Insert Chroma Key
2. Use dropper to grab good sample of weird tinge color, then adjust thresholds for optimum mask
3. Duplicate track and delete Chroma Key on second track
4. Insert HSL on second track and zero out the saturation
5. Insert Brightness and Contrast on second track and adjust for natural look in areas showing through the first track's mask
It's not perfect. It doesn't fix the altered contrast but it does greatly improve my footage by eliminating the weird tinge of color caused by my camcorder's infrared sensitivity.
Before and after: