Let me explain about trials, a trained acupuncturist does not put needles in at random, there are VERY specific places which are used depending on what is being treated and on the patient him or herself.
So in a double blind trial, they have people inserting needles at random so unless the patient has an understanding of acupuncture, they won't know the difference.
If you want to know more, acupuncture works on a theory of meridians or lines of what the Chinese call chi (energy) running through the body. There are 12 of them, they relate to the organs, to the physiology of the body and to the mental and emotional state of the patient, amongst other things.
It has now been scientifically validated that there are such pathways in the fascia, the web that wraps us up inside our skin, and that acupuncture points where needles are inserted are measurable points of lowered electrical resistance.
How do I know all this? Because I studied acupuncture for my anthropology undergraduate dissertation (in the 1990s) and was so impressed that I went on to study it at Masters level and to have acupuncture regularly myself.
Acupuncturists have always completed years of study and now complete a degree course in order to practice. They undertake regular CPD. Physiotherapists now sometimes take acupuncture courses but usually only for a few days so their depth of knowledge is much less. Just like conventional doctors, some will be better than others. What amazes me is how the Chinese knew what they did 2000 years ago.