First thing to rememeber is that there is no variation of degrees of het, the animal either is a het or it isnt. That's usually where the confusion with this comes from.
When you breed a normal to a het, half of the offspring should be hets and half should be normals (statistically speaking). But since you cant tell by looking at them which are hets and which are normals, they are sold as 50% hets, meaning that each animal has a 50% chance to be a het, but also the same chance to be normal.
When you breed a het to a het...albinos for example... the babies will statistically be 25% normals, 50% hets, and 25% albinos. However, the normals and the hets all look the same, and are sold as 66% hets because there is a 66% chance for each baby to be a het.
That help any? Sounds complicated, but its really simple once ya get it. 
Nicole