I have seen this before, Luviesmom. I have not done it, but wonder if the results are the same or different if one strips clothes washed only with detergent in the same fashion. IMO that is the only way to be sure that the DIY laundry soap is really the culprit. Without a control, scientific testing is pretty much just a guess. I would go so far as to suggest that a new and not yet worn item be the control and that two other items be the test for comparison puposes, where the other two have each been washed the same amount of times in their respective washing solutions. That way one would really have a better idea of any actual difference that there may be.
That all seems a little beyond the route I really want to go, so I've never done it, but I have thought about doing it, just so I can make up my own mind. Until I do, though my mind remains skeptical on this issue. I am not saying your results were not remarkable. They were, but IMO without something else testing the same level of use of regular laundry detergent, I still believe it is an inconclusive test. By the 'same level of use', I mean laundry that was washed with only detergent after undergoing the same amount of wear and exposure to body odor and dirt and washed the same amount of times as the other laundry tested.
It is an experiment worth doing and since I feel so strongly about the need for a more scientific method to obtain the empirical data, perhaps I really should do it myself. But I don't own any detergent and I am not sure I really want to go through all the necessary steps to do this. The steps would require me to purchase at least 3 new fabric items and subsequently expose 2 to the same rigorous getting dirty test and washing separately in the 2 different washing methods the same amount of times before doing the stripping of all 3 (one, the control, never having been worn or washed). That's a lot of dedication and work. And then what kind of item would be suitable for such a test? Something like a towel, that is actually relatively a not-so-dirty item in the laundry? Or something like undies, or something like a shirt that gets armpit odors embedded, or something like, well the list goes on.
Let's face it, I think it's a good idea, but I'm not motivated (at this time) to undertake such an experiment. :think:
And, P.S. I am not offended by your post, or your results. It's surely a valid point to consider.