Hmmm yeah, so I only smell something when Boulder smells something. The slaughter house pretty much never smells (though there are times), and the feed lots that produce the majority of the smell are all well outside of the city. Take a look at this map:
https://www.google.com/maps/@40.3847013,-104.64311...
JBS Five Rivers Cattle Feeding is one of the known problems. So, the smell is certainly NOT FROM GREELEY. Any beef, pork, or lamb you eat probably came from Greeley, but the meat industry is such a small component of the city, that I only remember its there if I drive past the plant. Actually, Greeley is really a great town with a wide variety of offerings and I'd be happy to go on a rant on how it is far superior to Fort Collins, Boulder, Denver, etc. etc. in a wide variety of ways...