Yes, the locations can be and have been tested. The needle action itself is what can't be properly tested, though there have been plenty of attempts with various types of sham needle, etc. I'm not trying to claim it doesn't or can't work (since I don't know), just that it's frustratingly difficult to research important bits of it.
You can compare to to deeper (in safe) or shallower insertions, and not tell the patient which is official acupuncture. You can apply anesthetic s first. These give clues.
