For pure gore, and zero story i recommend The Devil's Experiment, The first & goriest of the Guinea Pig series. It is basically torture from beginning to end, and I have to say some of the best special effects make-up (before The Walking Dead). And no RAPE!
Personally I liked Wicked Lake, but I am partial to Al Jourgenson, and any movie he is either in, or does music for I tend to like.
The Last Horror Film (which can now be found on Troma Retro) is one of the best written horror films I have ever seen, very creative, and the twist is straight out of left field.
Knight Chills for pure jokes, this is a movie made by Christians to show the horrors of role playing. Not really gory, not really good either, but funny to say the least.
Once you get desensitized to horror, really the only option left is to just watch the cheesiest stuff out there, Troma, Fangoria, & even Maple have a huge library, some are just horrible and not worth the time, others are so bad they are funny, and the rare gems are really great movies.