The tip-off is that the promoters either never have a scientific explanation of the details, to show why it is or would be possible, or their explanation is incomplete. Or they begin to act squirrelly if reasonable questions are asked. Questionable accomplishments even get significant scientific and industrial notice, before they mysteriously dwindle into obscurity (usually related to odd financial maneuvers of the proponents). An example of this was Andrea Rossi and his cold fusion gadget, the E-Cat. (Here's a good run-down: https://skepticalinquirer.org/2019/05/rossis-e-cat-expose-of-a-claimed-cold-fusion-device/) We had the E-Cat come up for consideration at my company, but making sense out of it was elusive. My best guess at the time was that the process might have been the stimulation of beta decay in the construction materials, transforming nickel into copper. Alas, no joy.
I want to argue but your reasoning is solid. Slight of hand.
The tip-off is that the promoters either never have a scientific explanation of the details, to show why it is or would be possible, or their explanation is incomplete. Or they begin to act squirrelly if reasonable questions are asked. Questionable accomplishments even get significant scientific and industrial notice, before they mysteriously dwindle into obscurity (usually related to odd financial maneuvers of the proponents). An example of this was Andrea Rossi and his cold fusion gadget, the E-Cat. (Here's a good run-down: https://skepticalinquirer.org/2019/05/rossis-e-cat-expose-of-a-claimed-cold-fusion-device/) We had the E-Cat come up for consideration at my company, but making sense out of it was elusive. My best guess at the time was that the process might have been the stimulation of beta decay in the construction materials, transforming nickel into copper. Alas, no joy.