I've just been reading 'Eating Animals' by Jonathan Saffran Foer. It's a very straightforward look at the factory farming industry in contrast to the "old fashioned" way of farming.
Evidently "air cooling" is the norm in Europe and Canada, but the industry in the US has fought to keep water cooling (where hundreds of carcasses are chilled in the same bath, with feces and other contaminants) because they absorb 8-11% of their body weight in water (bacteria laden water), and then sell the chicken and water to the consumer. In other words, it's more profitable to do things the dirty way.
Animal welfare aside, we owe it to ourselves to learn exactly what we're being sold and fed.