We all hear about pigs being so much more reviled than other forms of non-kosher. This is true in general culture; I believe such a minhag was recorded with regards to using soap rendered from non-kosher animals; we find the Talmud occasionally referring to a pig euphemistically as "something else", rather than having to say the word. What's so special (in a bad way) about pigs?
A few thoughts come to mind; this is a wiki, so please add more:
The essay brought here discusses why we revile the pig more than any other non-kosher animal, connects it to our own spiritual service, and explains why it will specifically be the pig that our Sages say G-d will make kosher again when Moshiach comes (as discussed there).
In short (but read the essay for all the details). The pig represents the worst kind of evil, evil masquerading as good. That is the hardest kind of evil to fight. However, the fact that the pig can successfully masquerade as good must be because it has some good in it. our severe hatred of the pig serves to cut off the evil and leave the good. On a spiritual level, this represents our fight with our own evil inside of us, the animal soul. The pig reminds us that we too have an evil inclination inside of us and by fighting it, we can leave only the good, eradicate the evil, and prepare ourselves and the world for Moshiach. G-d will reciprocate by making the pig kosher.
As discussed here, that doesn't mean the pig will actually be Kosher when Moshiach comes, depends on who you ask.
There is an amazing Ramban in דברים ,פרשת ואתחנן ,פרק ו, פסוק יא. The Ramban comments on the verse that says that when the Jews go to Israel there will be houses filled with every "good thing" (בתים מלאים כל טוב). The Ramban explains that this is referring to "pickled Pig". He explains that the Bnei Yisroel had a permit to eat pig. He quotes those that suggest this permit lasted for seven years. It is worth going through the Ramban. However, it is clear from this that the verse is referring to Pig as a "good thing". Furthermore, if it were as bad as people make it out to be, then how could Hashem permit us to eat it?
It would seem from a Halachick and philosophic standpoint their is absolutely nothing wrong with pig. But, what can we do, Hakodosh Baruch Hu forbid us to eat it. It seems there had to be some class of foods that are prohibited, Why pig? I don't know. But we see from the above Ramban there is absolutely nothing intrinsically wrong with pig per se other than Hashem was גוזר on me not to eat it.
Something I wrote at Parsha Shemini last year
The 172nd prohibition according to Rambam’s Sefer HaMitzvos is the prohibition against eating non-kosher. In Volume 3, Chapter 48 of Moreh Nevuchim the Rambam writes ‘if we were allowed to eat pig’s flesh, the streets and house would be dirtier than any cesspool’.
Have you ever wondered why it is that in almost all stereotypes about what a Jew can or cannot eat Pig is more often than not singled out? Beyond that even with Jews that aren’t so strict in keeping dietary law they will proudly say ‘I don’t eat pig’. What is it about the Pig that singles it out amongst all other non-kosher animals?
In Parsha Shemini we are taught that in order for an animal to be kosher it needs two identifying signs, to have cloven hoofs and to chew the cud. The Torah does not list those animals which have both signs and are kosher or those which lack both and are not kosher but rather the only 4 animals that have one of the two signs.
It tells us that the Camel, Hyrax and Hare are not kosher because they chew the cud but do not have a cloven hoof and therefore unclean. The Pig on the other hand is singled out as being the only animal that has cloven hoofs but does not chew the cud. It is worthwhile to note that over the past 2400 years there has never been another animal found that fits into one of these categories.
So we see that the uniqueness of the Pig is that it is the only and will be the only animal to ever have cloven hoofs and not chew the cud. The question is why it is still held with such disregard by Jews, what makes it more unkosher them the next, or more unkosher then the Camel, Hyrax and Hare.The disregard shown for the Pig even finds its way into the Talmud, Midrash and later Rabbinic literature. The Midrash Rabba uses the Pig to refer to the evil national of Rome. The Midrash Tanchuma when describing someone drinking uses the analogy of animals. Drinking one cup a person becomes like a lamb, modest and meek, two cups mighty as a lion and speaks with pride, three to four cups like a money who dances and frolicks around and when he is drunk he becomes a pig, dirtied by mud and wallowing in filth.
Unique to the Pig amongst all other non-kosher animals is the appearance of being Kosher. The Pig is the only animal whose hoofs are split appearing from the outside no different to any other kosher animal but what lies beneath is its non-kosher inside, that it doesn’t chew the cud. For Judaism, nothing could be worse than making a holy facade when your inside is rotten. It is this very attempt to parade itself as kosher which gives it the status amongst all other non-kosher animals.
The midrash asks the question why is the Pig called the Chazir? For in the future it will be lehachazir,returned. i.e. that Pig will be kosher in the Messianic Era. How is it after all that we have seen the Pig will become kosher in the times of Moshiach? Surely that is a time for eradicating animals that masquerade as one thing and are really another. However Kabbalah and Chassidus teach us that the pig does something for us, it forces us to confront our own short comings, and our own masquerades. We are the same on the outside all holy and pure but inside all rotten. We should strive to recognise the pig from what it is a mirror of ourselves.
It is taught that if we perfect ourselves and allow our outside and inside to be aligned that HaShem will do the same for the Pig. So it makes sense in times of Moshiach the pig’s inside will be as pure as the outside, it will chew the cud as well as have split hoofs. We can speed up the process by working on ourselves.
I've thought about this for a while, and perhaps is has something to do with Yeshayahu 65:4. In that chapter, G-d is talking about how much he is upset at those who "vex Him to His Face" and (if I understood it correctly) will destroy them from amongst His people, while saving the righteous.
In verse 3 and 4, the prophet enumerates a list of things G-d says people are doing to vex Him, and amongst them is "those who eat swine flesh".
So eating pig is singled out (along with 4-5 others) from all the transgressions.
Perhaps because of this, pig is so reviled.