If you let them sit in a heat lamp they have the potential to start to bloat and rot. I defrost mine in the fridge over night, then just on the counter for an hour, then I heat it up with a hair dryer. Some times the belly feels really super soft, those a pitch. The ones that feel more or less like a fresh kill I throw back in the freezer in a separate bag, then I will defrost and try once more, if that time it is still refused I pitch it.