What does listening to a speaker really tell us?

Ok. I got lots of advice here from people telling me the only way to know if a speaker is right for me is to listen to it. I want a speaker that represents true fidelity. Now, I read lots of people talking about a speakers transparency. I'm assuming that they mean that the speaker does not "interpret" the original source signal in any way. But, how do they know? How does anyone know unless they were actually in the recording studio or performance hall? Isn't true that we can only comment on the RELATIVE color a speaker adds in reference to another speaker? This assumes of course that the upstream components are "perfect."
Fabulous topic with existentialist leanings, I love it!
For mine, we walk a tightrope in "Audiophilia". There is this side that says "accuracy" is what we need, that what comes out of our speakers is as close a reproduction of what is going on upstream. What IS this accuracy thing anyhow?
If I want a "kind of accuracy" I can get vanishing-low thd from a seventies integrated SS amp with bucketloads of feedback. But does it "make music"? Not for me.
As for the "musical" thing, what is that? What makes a musical "connection" to me is another person's poison.
Recreate a "live sound"? This is always our reference point, it must be. Someone alluded earlier to the notion that live music "kicks your butt" or to that effect. Doesn't it though? There is nothing "polite" about a trumpet played with passion. So for me the "smooth, laid-back sound" doesn't cut it, it doesn't kick my butt. For others, that kind of sound just might "welcome them in to the performance". So be it.
So for me, I want a speaker that makes it all "HERE!", as much as I can.
Never having been blessed with a system that simply Does It All, I make my compromises how I think they work best for my way of appreciating the performance. In a way, since we can't get a "perfect" speaker/system that it voices, you kinda choose your coloration, and the more we do this audiophile thing, the better an idea we have of what that is, referring always back to live music.
PBB, I didn't forget you. One of the basics of sound reproduction and perception is that the ear's sensitivity to frequencies changes with the sound pressure level. Ever notice that there's a just-right playback volume? For example, below that level there's not enough bass, above it there's too much. That's your ear at work. In the context of this thread this means that the elusive wild goose of transparency can only occur at one volume setting for each recording. At all others the perfect system will sound out of balance, and so by definition, non-transparent.
Absolutely, Rockvirgo!
For this reason, in a practical sense, I'd rate a remote volume control more important than a "technically superior" one in most circumstances.
There seems always to be the "right volume", although the best systems seem somehow to work in a wider range of "close enough".
This is not a pipe.(The picture says,wanting to convey that it is a picture of a pipe.) If it makes you hallucinate the aroma of tobacco, if it gives you a nicotine-like rush,it's a good picture(maybe),but it's still not a pipe.

Music is a time art.Once performed,it is gone,never to be experienced again. We can replay it,if it was recorded;but live music and recorded music are two different things.

(turning up the gain,listening to a recording of the Max Roach/Clifford Brown Quintet,wishing everybody a good morning.)
My question would be, if you can't tell what it sounds like when you listen to it, then how else could you tell?

We already know that no stereo system, no matter how good, actually reproduces the live event totally. Nor is there any recording sytem that captures it totally.

So, what we are after is what sounds the most lifelike possible, to us, and in our price range.

Or, in some cases, like your analogy supposes, there are some who would prefer some other "interpretations" or colorations to the presentation.

In any case, it is what the system sounds like to the owner which is most important to him. This makes "listening" the paramount benchmark of performance.