You bring up some good points about obscenity laws, and the confusion surrounding them.
I tend to come down on this side: as long as the actors are of age, and not forced to perform in any way (that is, "mainstream" porn), I have no problem with it. Erotica by itself is not harmful, and in fact goes back way before film was even invented. Certainly, watching attractive people have sex is not in and of itself evil.
However, the "squish" movies and the other forms of "snuff" you mention are most definitely beyond the pale. I'm not as certain about that which is faked...while those who prefer to watch it are probably worth keeping an eye on, no person or living thing is actually harmed. I don't think it wise to go after what amounts to clever special effects...quite a few mainstream movies would be affected, like Saving Private Ryan or Black Hawk Down.
CH has actual scenes of animal cruelty. That major chains showed what was at one time an extreme example of independent skid row exploitation cinema shows how much the culture has declined (in part due to jaded postmoderns). Postmodernism DIED on 9.11.2001 when people saw genuine horror and evil yet within a week they wanted to go back to the way things were and by 2 weeks were watching Letterman again and starting to claim "Bush Knew" as well as telling tales of Timothy McVeigh types hijacking the planes.