Two points before I begin:
1) I think a reminder is in order that
we have a thread dedicated to lolcats.
2) Anyone remember the unofficial rule that you can't complain or call a repost unless you post a funny in the same post? Yeah, those were good times.
It's mostly that they are more comfortable to eat with their own filth compared to other animals that makes me gag a bit.
So, you find that the Pulp Fiction description of pigs is accurate? I had an uncle that raised hogs, and was an active member of the Kentucky Pork Producers. I can tell you from experience that pigs are very clean animals, more-so than dogs, and would prefer to remain clean, however they are unable to sweat properly and thus need to find a way to cool off. They use water or mud to do this, not their own filth. However, a cramped farming environment will cause the mud and the filth to become mixed. Does the pig then wallow in the filth mud mixture, yes, but not because it loves the way its filth feels. It is a matter of life or death, via heat stroke.
Tell me, if you had a choice between smearing poo on your skin or dying a very painful death which would you choose?
http://www.depts.ttu.edu/porkindustryinstitute/research/MANAGING HEAT STRESS IN OUTDOOR PIGS.htm
The sparse hair coat facilitates heat loss from the skin surface of the pig since the pig’s skin is open, unimpeded by hair, to evaporate water. The trouble is, the pig does not have functional sweat glands on its skin.
The pig has a form of sweat gland on its skin, but they do not work. The pig can lose a small amount of water, and thus heat, through passive diffusion through the skin – but not much. So instead of sweating, the pig uses behavioral thermoregulation to cool itself. Behavioral thermoregulation is actually a more powerful mode of heat loss than is sweating – and the pig does not become dehydrated. Behavioral thermoregulation is an effective means of cooling as long as the animal has access to cool substrate.
Sows in fact prefer a cool surface to lay on (Bull et al., 1997). They actually preferred conductive cooling to other forms of cooling (water or cool air). Thus the domestic pig seeks cool surfaces and would be comforted by cool surfaces both by reducing heat gain (by exposing their body surface to cool rather than warm surfaces) and by the cooling effect of the water and mud.
And your point on other farm animals is very accurate. Chickens in cages barely have room to move, same for rabbits. Cows stand in their own filth if not at pasture. Do you like shellfish? And dogs eat their own poo.
Truth is that pigs are like you and me when it comes to cleanliness (well, me I don't know your personal hygiene) more than the pets we allow in our homes. They are so close to us in fact that I once had a valve from a pig in my heart. They are very much like us, well, with one very important exception:
A HUGE CARP!!!! 
