This is a bit long and it gets into details many people will never think about, but....
The first part is what I was saying- they probably don't know how inaccurate their speakers are, but they often decide to look for something different after hearing something better. I know I did- my system was better than anything we'd had at home before but once I started hanging out in the dorms at school and heard what some of the others had, I immediately started messing with my speakers and trying to improve them.
The tricky part about listening to acoustic instruments is that, even if all of the recordings are accurate, the sound of different brands of guitars, pianos and others sound different, so it's not possible to base the sound on the generalities of "it has acoustic guitar" when one track has something from Martin, Gibson, Taylor or other brands- they all have their own sound. Then, there are the mics and other processors. I think it's best to listen with naive ears- don't be obsessed with the fine points, just listen to the sound and listen to a wide range of recordings. As a couple of examples, listen to Keb' Mo' and Allison Krauss & Union Station- the instruments are recorded extremely well, IMO, but they use different brands of guitars- Keb' Mo' uses & endorses Gibson, Dan Tyminski uses an old Martin and I assume they both use mics and transducers, but I don't know for sure. Then, listen to other music, where there's no real clarity to the guitar sound, although it may fit well in the mix- best to listen to music that features the instrument, rather than mix it up and compare something where it's front & center vs background.
I didn't mean that people should be steered toward more expensive speakers by the salesperson as a tactic to make money but in the AV industry, they preach that it's easier to get someone to move down than it is to move up to more expensive items. THEY'RE all about making money, I have always been into getting the best sound for my customers, based on their budget and other requirements.
The good thing about all of this- our minds allow us to become accustomed to sounds that aren't necessarily accurate if nothing changes. Listen to a stringed instrument and over time, the sound changes because strings age. Listening to the instrument on a recording changes nothing, so that sound is fixed but one thing that frustrates me with my acoustic guitars is that the strings have a small window where I really like the sound and the rest of the time, it's hard to be totally happy with the sound. New strings sound very bright and older strings sound dull, but as a background instrument, bright strings is sometimes exactly what's needed, while dull-sounding strings punch through for playing rhythm, so there's no "always perfect".