What do raw pork neck bones smell like?

I've always used a basic rule of thumb for any meat, fish, poultry or bones: there should be no odor at all! I make a lot of bone broth and throw the bones in a Ziploc bag after removing the meat, then into the freezer they go! Once I have enough bones, I throw them in a pot with seasonings and cover with water. Add 1-2 tbsp of apple cider vinegar (organic with the "mother" is best), let it sit for 30 minutes (helps draw the nutrients from the bones and doesn't affect the flavor at all), then bring to a boil, turn down the heat so that the broth is barely simmering, and let it go for 48 hours. Some cook for only 24, I just think more time = more nutrients.