Smell is just one way to know when a food is o.k. to feed, but certainly not the only way to know if a food is safe to feed. Kibble doesn't smell very good to begin with, but when it has gone "off" it smells even worse. Depending on the kibble base and main ingredients, and the problem, there can be several tell tale odors that indicate the kibble is not fit for consumption. Considering how olfactory oriented ferrets are - they are able to detect odors we cannot and if they refuse to eat a particular kibble it could very well be that the kibble has gone "off" but not to the point our human noses can discern. People who regularly wear perfume, cologne or scented clothing or who smoke are at an olfactory disadvantage. So a kibble could be well gone before they notice; but the ferrets can pick up on the turned food very quickly. If the kibble has a high fat content and has not been stored correctly the fats and oils can go rancid. The best way to describe a rancid fat smell is it will smell like the old, nasty, trash oil dumpster behind any McDonald's or Burger King or Chinese restaurant. If the kibble is a potato flour base and has gone "off" there may be a pungent dirt smell with sickening sweet overtones. A corn based kibble that has gone "off" may smell quite moldy or even like alcohol. A kibble with lots of fish meal that has gone off will really be nasty smelling indeed, combined odors of fish and rancid oil - will take your breath away. A kibble that is infested with grain mites will smell yeasty and the mites will look simply like white or beige powder, until you watch closely and can see the powder moving on its own and following little trails! Some kibble will have grain moths, beetles or meal worms. Often this kibble will look like there are spider webs, or cotton filaments. Depending upon the infestation there may or may not be an odor yet. When the infestation is well advanced there will be a musty smell. Kibble that has gotten wet will definitely smell moldy and may even have mold or fungus growing from it! Other indicators that the kibble has gone off, besides smell, can be color, texture, and form. If any differences are noticed, do NOT feed the kibble. Wash your hands thoroughly as well as any surfaces and utensils contacted. Reclose and seal the bag and return it to the store. I would contact the manufacturer and let them know about the problems found. Problems may not always be from the manufacturer - they could arise during shipping, handling, storage, retailing and even consumer mishandling. But to be safe it is wise to note the manufacture date, expiration date and lot number of the product. Although it may look good for the budget, buying kibble in bulk is not always a good idea unless you have lots of freezer space or lot of ferret to feed. Transfer the kibble to an airtight container (or several) save the bag label with lot# and expiration date. Tuck it in to a container, mark the other containers. Only mix together what you can feed in a week and keep this container in the fridge. While I don't feed kibble anymore, (all my ferrets are natural feeders) I have fed kibble throughout my lifetime to the zoo of animals that have been my family and have run across first hand, many of these gross smelly kibble issues. Regards, Kim [Posted in FML 7818]