Thanks all! That sunglow male is my favorite animal I produced last season.
Sirens - She's staying right here unfortunately, sorry!

I use a Nikon D50 with an upgraded lens (Sigma 18-50 2.8). All my photos are white balanced using a whibal card:
That's a bit different from what you were referring to: exposure. Alot of times to expose the subject correctly the background must be slightly underexposed. This is because of the low dynamic range inherit in all cameras. Take a look at this photo:
Notice how the upper right corner is bright white and the lower left corner is not? You're seeing the exposure range of the camera from corner to corner there. If I expose any higher, much of the photo will be overexposed, resulting in washed out colors on the albinos and reflection points that are unviewable. If I go any lower it will be just too dark. There's a fine line of perfect exposure that can be somewhat difficult to adjust to.
I occassionally see people take boa shots and exposure for the background. Making the snake look way too bright. Most of the time this is done using boas that are not very light in color, ie not albinos. It yeilds a seemingly satisfactory result because the boa looks great, much lighter than it should most likely (ie not as accurate as it should). With albinos it will just wash away all their color and the innaccurate results are too apparent for anyone to miss.