I've seen or heard of all of these films, but it is interesting to see someone like MovieBob shine a light on them for those who are unaware.
I'd say, personally, that "Visitor Q" is worth a look, though it really is Miike at his most disjointed. "Audition" is probably the best complete film that he's ever made, so I'd recommend that over "Visitor Q". Another good Miike movie for the bold and curious would be "Imprint", though if the mental image of dead fetuses is too much for you, I'd suggest avoiding it.
"Salo" is a mediocre movie, really. It has the ambition of a great film, but ends up getting stuck in the muck and the mire. It never realizes its fully potential, which is unfortunate, though it is disgusting if that's all you care about.
Also, if real-life animal death is something you can't stomach (and who can blame you; I hate seeing it myself) then DO NOT WATCH "MEN BEHIND THE SUN". There are scenes of cats and rats dying, and an autopsy scene that featured the actual corpse of a dead child. The movie was shot in China, and the Chinese authorities were willing to let the crew shoot an honest-to-god autopsy. Once you learn that, it makes the movie even more disturbing. It's a powerful movie, but I can't recommend it since its graphic scenes are truly disgusting.