In manual therapy one is taught that one can push bits of body around, and that this makes them feel better to the person whose bits one is pushing.
I call this the "operator model" of manual therapy.
One quickly learns (or should) that manual therapy is much less about the bits one thinks one is pushing, much more about one's speed and force, mostly minimalizing thereof, waiting for the opening, waiting for the person's physicality to let one in.
I call this the "interactor model" of manual therapy.
However, it's quite possible to remain stuck in the operator model for good.
As one proceeds through life one begins to realize that it is impossible to prove to oneself or anyone, through any method, specifically scientific but also logical or philosophical, that what one "thinks" one is doing has any bearing on reality. I.e., you cannot prove, even to yourself, that the SI joint, actually is what you are "feeling" with your fingers, as you perform what has been taught to you as a "test" of its "function." Yes, you can feel stuff... stuff is moving, or not moving, but what one feels moving or not under one's fingers, from on top of skin, has absolutely NO bearing on whether or not a buried SI joint is literally moving. There are many layers and structures all moving on each other between skin and joint, even inside "skin" (cutis/subcutis) itself.
It's merely a convenient assumption. It's a belief. There is absolutely no way to show that it is or isn't moving, or that people can or can't palpate it clinically.
In this case, what do you do? You realize (with a sickening feeling) that you've managed to paint yourself into a conceptual corner. There is no way out, except:
1. ... tromp out over wet paint, spreading dirt and paint.
This is the equivalent of insisting that it's possible, it must be, you've always thought so, your patients' results have always verified your magic-hand ability to ferret out movement/non-movement in the SI (except for when they didn't), therefore the premise must be right. Right? (Those patients who don't fit, well, there are always a few patients who don't fit, outliers, right? We can ignore them, can't we?) Wrong.
Trying to set up tests to "prove" you are right/how right you are is a version of what Harriet Hall calls, tooth fairy science.
2. ... admit defeat, stop thinking about escape, sit in the corner, deal with your feelings, and wait for the paint to dry, however long that may take.
This is the equivalent of waking up yet another rational level on the manual therapy mesodermal mesmerization coma scale, reconfiguring/allowing reconfiguration of your own mentation to accept the facts as they are, including that you were a victim of your own conceptual hallucination, perceptual fantasy, that you were dreaming your own bad-logic dream. But it's OK, you're more awake now, and can move your mind differently, more reasonably. You can now reinterpret your work more correctly as interactive with somebody else's neuromatrix, and whatever it is you think you felt in the past, can go ahead and just be whatever it is/isn't, a mystery of function/dysfunction, not having to have any anatomical identity whatsoever. It will change anyway, just like patterns in clouds change. Continuously. That's a good thing, especially when the patterns are associated with something feeling 'wrong'.
Especially freeing is to know you don't have to prove anything, because there is nothing to prove. Instead from now on you can sit back and disprove, which is a heck of a lot more fun.