Pigs are some of the cleanest animals on Earth. The reason for this is that they refuse to excrete near where they eat or sleep.
While pigs in captivity have no choice but to excrete waste near their living spaces, wild pigs refuse to do so.
They often wander far away from their den when nature calls. Unlike humans, pigs do not sweat. They wallow in mud to cool their body temperature, which gives them their dirty appearance.
Pigs are also very smart and can be trained very much like a domestic pet. When properly trained, pigs can obey commands.
Source:reference.com
