There has been a recent thread on favorite martial-arts, which referenced an old thread on hated martial-arts. So, how about martial arts which you don't necessarily like or dislike, but have particularly nasty entry requirements - I guess you could call them 'disgusting martial arts'?
- The archetypal entry is probably the Sunflower manual, which requires self-castration. 'Nuff said.
- The 1,000 spider 10,000 poison hand - you have to let poisonous spiders bite you to absorb their poison, which makes you look increasingly hideous as the poison accumulates.
- 9-yin white bone claws/heart-piercing palms - misinterpreted 9 yin (or not - hard to tell in the 3rd edition). Practiced by shattering a living practice target's internal organs with palm strikes, clawing holes into their skull, then cutting them open to see how well the palm strikes did. Lovely.
Going outside of Jinyong novels:
- The silkworm art from Reincarnated - before you complete it, your power comes and goes without warning (usually at the worst possible moment). To complete it, you have to be beaten to within an inch of your life, die, then be reborn. Alternatively, some else can learn it and then give it to you (losing everything in the process).
- The Yuan-yin art from the 80's TVB remake of 'The Legendary Twins' - you have to eat the flesh of your own blood-relatives to learn it. Jiang Bieke ended up eating his own son.
- There was a Hong Kong wuxia series from the 80s that I can't remember anything about (not even the name) except for the main featured martial art - to learn it, you have to cut off your own head. Of course, if you do it right, it can be reattached to your body again will no ill-effect. If not, well... Can anyone remember which series this was?
- In the novels of Liang Yusheng's Tianshan saga, all practitioners of 'evil' martial arts are guaranteed to fire-deviate in time, without exception, unless they acquire the inner-power formula of 'good' martial arts. Most of the practitioners know this (they actually openly call their own martial arts 'evil sect' arts) - yet they go ahead and learn it anyway...
- Jade-maiden art from The Final Combat - if a man learns it, they become a not-man, not-woman freak.
Any other notable contenders?