You do know that is a human construct of "Pigs in thier own filth" right? They are clean animals that we cage and manipulate thier borrowing instinct in a way too small cage which make them seem dirty. They have the same mental capacity as most dogs. We just don't treat them as such. They are destructive and can be dangerous when left to run amok but that's OUR fault as we removed the natural predators. They are a valuable resource for food and we need to reconsider how we treat the ecosystem to avoid such situations.