Technically, the best that can be said is that like any placebo, they can work pretty darned well. Parents use placebo treatments with kids all the time because they work. :)
A fair point, but then you might as well just administer a simpler placebo without the woo :). In the case of homeopathy that would be asking people to just drink a little water.
Anyway... IIRC the current consensus is that the "more extreme" the intervention appears the more beneficial the placebo effect is, so...
