Most responsible snake owners would not choose to feed live food to their snakes if at all possible. Even if you have no compassion for the prey, most rodents are surprisingly capable of quickly inflicting quite a bit of damage to a snake when they are frightened. However, there are some snakes out there that no matter what will not take prekilled or frozen/thawed meals. I have 2 rescues that were raised on live, and after trying every trick in the book I still have not been able to make them take anything but live. I won't let these two mistreated and abused animals starve to death simply because I have moral qualms.

It may be an awful situation, but a 'serious attitude' displayed at work may not be the best response. If it is someone who is callous enough to enjoy feeding live, it will only make them more belligerent. If it is someone who is having to choose between letting their pet die or not, whether or not you agree with their decision, I personally don't feel giving them any more guilt or grief is warranted, especially when you are on the clock.

And as far as the food animals' pain or suffering, I think a snake tends to be faster and more efficient at what he does than some of the 'mice-cicle' companies. Some use more responsible methods, but there are also some pet stores and suppliers who simply throw live rodents in the freezer to freeze to death, or deliver blunt trauma and wait for them to stop twitching.