This is probably the single most disappointing thread I've read on this forum
"I saw someone use rods and find something" /= proof
"Some buried things generate magnetic fields" does not explain why one should supposedly use coat-hangers, pvc pipe, or even wood as detection devices over sophisticated scientific instruments.
And unless I've missed it, none of the believers in the rods has addressed why multi-national gas and oil firms ignore the rods, but your local 'old timer' farm hand has supposedly mastered them
Sheesh...
EDIT:
This is also true of, say, chemotherapy. That doesn't make it untestable. It should be trivially easy to have the people who claim it DOES work for them to do some tests where they show a statistically significant improved rate of success, even if that falls short of 100%.