Okay, (sip of coffee first), the way people who breed a small amount to sell, and how the really big rodent companies do things are different. From websites they say, "Rodents are humanely euthanized and blast frozen to maximize freshness". CO2, and then blast/flash freezing is different then snapping the neck, or even making a CO2 baggy, then putting them in a regular freezer. I have 300 mice in my freezer right now, 3 different sizes in 3 different bags. I don't see one turd in there. No urine stains either. (Just some extra broken pieces.) I might actually buy from somewhere else next time to get them vacuum sealed. Its not that I'm that picky, or need to be, but when I have options (all online for about the same price), I'm going to go with what is better. The cheapest sources of mice for me, other than breeding my own, is the big online breeder companies. The frozen mice at my local pet store sometimes smell a little and have substrate or even a little feces on them, which I understand. No biggy. They also cost 3 times more. When I need one big mouse for my one adult, I go get one of those because its convenient for me and its fresher than buying in bulk. But when I buy 3 months worth for a big group, then online (which is flash frozen, etc) is way cheaper (and better). BTW, the most expensive way to go is the arctic mice from Petsmart which are nasty when dethawed.