The guys over at Horroretc recorded a nice, long podcast a couple of weeks ago covering a selection of films they deem to be the most shocking of the exploitation genre: The Texas Chain Saw Massacre, Last House on the Left, Cannibal Holocaust, I Spit on Your Grave and Thriller (the Swedish rape-revenge film, not Michael Jackson's admittedly brilliant music video).
The Horroretc guys are great reviewers, and I was pleased at their recognition of the use of sound as a horror device in a lot of these films - notably the constant hum of the generator in The Texas Chain Saw Massacre, and Cannibal Holocaust's incongruous, gently melancholic soundtrack, which adds a dimension of sadness to the all-out gore.
They see these films as grueling, difficult and very effective horror movies, but otherwise opine that they have little merit - before going on to contradict themselves in long discussions about possible meaning and director intent. This is most notable their review of I Spit on Your Grave, which they dismiss as despicable before descending into a heated discussion about its possible feminist angle. I love the way I Spit on Your Grave provokes this discussion every single time, without fail.