If the guts are coming out, I'm guessing the rodents are your problem. They probably were thawed and refrozen, are over 6 months dead, or weren't packaged air-tight. All of these are fairly common. If you got them from a pet store, it's the pet stores fault. I've had awful experiences buying f/t from pet stores. Try buying from another store or online, although shipping can be a bit pricey; they use dry ice to package them, which is fairly expensive.