I have to take Todnedo's side on this, no matter what - they are still wild animals.
You don't think that WC chams come into the country with countless parasites as well? in the wild Parasites are a part of the animals life, its not as if they are endangered of going extinct because of the parasite.
When CB animals with no resiliency are exposed to bacteria, parasites, infection e.t.c e.t.c then on the off chance it does occur - the outcome is much worse than an animal with an already established immune system.
Im not saying to let your cham rot its filth to build its immune system, so don't take it like that. What im saying and this primarily comes from my experience with birds -
When breeders raised birds in the *prefect environment*, the second something went wrong - aka power outage - the birds catch a cold, and they usually died.
Smart Breeders raise their animals to endure a little more, such that if the power goes out the bird gets cold, may catch a cold - but it can get over that cold in a day or two without any expensive trips to the vet. Its called Resiliency, and its a good thing.
Many can recall a time when Silk Worms were much hardier than they currently are - but over breeding and *pristine conditions* essentially destroyed the worms immune system, and now if anything goes wrong - bye bye colony.
People think "pet" and they think that somehow that term means the animal can never be exposed to anything - but in the off chance it is... bye bye pet, or hello expensive vet.
Do I agree with feeding the cham a gecko that big? NO. But do I disagree with feeding it a gecko in the first place? NO.
Im sure that in the wild it would eat anything that comes nearby - they eat not only insects, but small animals as well - birds - lizards, probably juvi rodents. Its the circle of life, and just feeding the animal an insect diet ( which I personally would think is more likely to be ridden with parasites than a healthy gecko ) makes that circle.... seem much more bland.
Further more if everyone is so abstain to watch the animal eat another animal, I would like to remind you that most of you are probably carnivores yourselves - and just because you do not go out and kill and skin your own cows - does not change this. You are still eating something that was once breathing, once had blood flowing through its veins - and if any of you have ever cooked your own lobsters or crabs - you don't need a reminder as to how hypocritical that is.
You shouldn't be so quick to condemn someone for something that you do every day yourselves in your own kitchen.
But thats just my two cents.