Companies make dogfood and sell it and expect others (dogs, who aren't known for verbalizing dissatisfaction with their food) to consume it. The producers of dogfood don't really care what it tastes like or how nutritious it is.

But I can't imaging a business which involves collecting farts and selling them to others and where sniffing a small quantity of each bottled fart would help improve production processes to ensure a better experience for the customer. And most people are appalled at the smell of others' farts but can tolerate their own, so the "smell your own" test wouldn't really tell you anything.

Eating your own dogfood is laudable - sniffing your own farts is not.