Thing is, they were the first to tell you they had no clue how or why they could dowse out water, but they could.
Sorry, until you've got a controlled study showing your little "witches" perform better than random chance, I'm gonna remain skeptical. Meanwhile, you should send one over to JREF... if her "powers" are real, she could win a million bucks!
Randi is (was?) an entertainer, not a scientist. His public "debunkings" have included such science as "if I can duplicate the effect through trickery it's fake" regardless of zero evidence that any such trickery was originally used. That's not a "controlled study," he starts with a known result.
I knew Delbert Merrill socially, he was an inventor and engineer who had a long career in industry. He tried dowsing when water couldn't be found on a property, and was successful. He developed a method swinging a pendulum over a map, and it seemed to work for him.
One night we were visiting him, and he showed us his rod. Two nylon rods, about two feet long and 0.1 inch diameter, similar to the nylon rods used to bind computer listings in those days. The business end was bound with non-metalic material, I think fishing line, and the hand grips were 1/4 inch bakelite (or similar) rigid non-conducting tubing, and the ends of the nylon had just been kinked 90 degrees to keep the handles from falling off. There was no way someone holding those bakelite handles could apply bend or torsion to those rods.
He walked across the property, saying that there was a stream in the area, and as he walked along the rods visibly bent. He offered to let us try it, and two of three people felt the tug, including me. The other person who had success was blind, could not have seen where the rods bent, and also got a strong bend at the same spot.
I never tried dowsing again, but Delbert Merrill did locate water on some property I was trying to buy, after three dry wells had been drilled. He predicted slight sulpher in the water, in an area not known for that, and predicted the depth within five feet and the flow within three gal/min.
I see that in upstate NY National Grid finds gas lines by dowsing as well as their little meters, the meters have false positives on any metal, not just gas lines. The sum of these experiences strongly suggests that there is an effect, sensible people like gas companies and engineers seem to find it usefully reliable, I wouldn't discard their experience casually.
Finally, Randi is an entertainer, some of the televised "debunkings" are far from scientific method:
- everyone can't reproduce the effect
- it doesn't work every time
- the effect can be created as an illusion by a professional
If those are valid criteria, they prove that pitchers can't throw a curve. Personally I'll put it in the "there's something there" category, since the people I have met who have produced measureable success make no money at it, don't care if people believe in it, and don't publicize the ability, I find profit, zeal, or fame to be unlikely motivation for trickery.