[Hamtastic]

Health is the main issue with hybrids. Because hybridization between Campbells and Winter Whites (they are different species, not just different colors of one) is not genetically advantageous for the offspring, you end up with babies that have obvious health defects (such as missing limbs) or more subtle health problems, like internal or neurological disorders. Predisposition to diabetes is also passed on to the winter white hybrids from Campbells. It's probably not as bad as crossing a zebra with a donkey, but it's still bad on the same principle. Just because cross-breeding is possible, it doesn't mean it should be done.

As far as what you get from chain pet stores in the U.S., those hamsters are already affected by inbreeding, poor food quality and nutritional value, poor conditions, and not breeding for health and quality. On top of that you get the hybridization (for winter whites and campbells). So you end up with hamsters that have a high risk for diabetes (or already come home with you having diabetes), likely shorter life spans, and predisposition to some other health problems, bad temperament being a lighter one.