The reason that homeopathy is so perfect as a form of quackery is because it is quite literally nothing. On second thoughts, I suppose that it’s not exactly nothing. It is, after all, water or whatever other diluent that homeopaths use (usually ethanol). However, thanks to some basic laws of physics and chemistry and a little thing known as Avagadro’s number, any homeopathic dilution greater than 12C (twelve serial 100-fold dilutions) is incredibly unlikely to contain even a single molecule of starting compound.
Science-Based Medicine » A truly homeopathic defense of homeopathy. It is, of course, also debunked in Deceived Wisdom.