Well thought out response, sir.
That being said. Addressing your points:
1-What is the "burden of proof"? Secondly, how do you define "wild claims" aside from the guy who said he had to turn down his sub by -4dB?
2-"Just because an RF engineer with a $40,000 Tektronix Lab Research piece of equipment says he can see an "improvement" in USB "packet noise", does NOT mean that anyone will be able to actually hear that "improvement" in the analog domain or there will actually be an "improvement" in the analog domain."
It also follows that it IS possible that there IS an improvement in the analog domain? No? Can't have one hypothesis without the other, no?
To answer your question: Sure, anything is possible. I don't discount the possibility that the ear can hear something which standard analog measurement cannot yet reveal. That's a real possibility.
When I talk about "burden of proof", I am referring to my own standards. I don't expect other folks to agree with my standards. Having said that, I do think any claim which says there are was a 4db difference is bass is 100% the product of placebo effect. I only use that as an extreme example to make my point. There are folks posting under the influence of placebo effect (PUI). I am sure I am guilty of having done it myself over the years. In my world, if I can't be certain of something, I don't ever make any definitive statements about it. Other folks don't have standards. They just say whatever comes to mind and don't think about how others may use that information for their own purposes.
I remember a couple of years ago, I got the very first totaldac USB cable. Vincent sent it to me for free because I was a good customer and had bought a lot of expensive gear from him. I told a few folks that I had this cable and they wanted me to write a "review" about it. I never really said much about it. The reason is that I can't be certain that it really improved anything in my system. I still use the cable in my system even though I don't own any totaldac gear anymore. But I would never recommend that someone else buy it.