This original post was incorrect. Most of the online negative press has been the result of one or two people hating on the dog food and making multiple accounts. It seems a lot of the negative press was in response to a false claim that earlier this year the food killed their dog (and they asked it to be spread around facebook). Since then, that claim has been retracted.
Reference: http://www.thatmutt.com/2015/02/01/kirkland-dog-food-update-man-admits-food-did-not-kill-his-dog/
http://www.thatmutt.com/web/wp-content/uploads/2015/02/Kirkland-dog-food-followup.png
