Sales involve a bit of showmanship but some dealers forget the sophistication of their buyers, especially in audio. Many years ago I witnessed a salesman at a high end salon doing his level best to convince a potential buyer of what he was hearing compared to what he was hearing. It was just the two of them up front and I was at the back but well within the better listening area which allowed me the luxury of moving around as the salesman spoke. What was described as a very wide and deep soundstage with great dynamics and extension had all the size effect of a TV screen. I had to bite my lip and walk out before the urge to say anything overwhelmed me.
The poor customer just sat there, nodding with his head but his face betrayed the motion and I think the salesman had a sale that day. We're talking Martin Logan speakers and AR separates with exotic cabling in an optimum set up in a room dedicated to stereo and it sounded like crap. So when I hear of problematic room set ups at audio shows I take that with the smallest grain of salt as there are others at the very same shows under the very same conditions that can sound fantastic. I believe that near field listening can pretty much help in determining the potential of most systems but in the end, you'll never really know until you hear it in your system.
As to B_limo's point, yes, I experience that most of the time. Even when I hear something markedly better that would require a sacrifice, of sorts, I'm quite content with what I have, in the context of where I listen, and wonder what all the fuss is about.
All the best,
Nonoise