well, sorry for the repetition to those who read about it in the other thread, but really i think that one can stand the 120 days of sodom only if you watch it bearing in mind that it was a political movie. probably if you saw, say, a very gruesome movie today about the abusive soldiers at guantanamo you wouldn't be overly impressed by the violence because you are very aware of the point it's trying to make, and most would be inclined to agree. pasolini made that movie to represent the corruption of fascist leaders, which at the time was still very fresh in the viewers' eyes (ok, he also made it for shock value, but the political intent came first), so they were not horrified by the disgusting scenes per se - they focused on the anti-fascist message.
i think that all movies that make extreme use of violent, sexual etc. imagery to make a statement that has to do with religion, politics etc. run the same risk - if the viewer lives several years or even generations after the events the film is commenting upon, or if s/he has a point of view that doesn't coincide with the director's, the squick value of the film stays, the message doesn't. it's different with war movies, as they're more universal - i found the beginning to saving private ryan quite sickening, in the sense that it was a trifle too gory for my liking, but eventhough the events in the film are historically distant from me they still relate to a concept that is always contemporary, ie war.