I know that taking a listen is always the best option, however; Room size, placement and the amp used all make a HUGE difference.
Whenever I go to someone's house to try out speakers (which has been dozens of times)
The speakers always sound different when I get home.
There's also the element of pressure and adrenaline when I go to someone's house that makes the speakers sound better sometimes. I've definitely gotten home and been disappointed, I've also gotten home and been extra happy. So since it's 50/50 with trials, I like to research before I even go listen.
The other factor is that, I've listened to speakers before and been totally blown away, wowed by them, and then over time when I have dozens of hours of listening time, find their weak points. I feel it would take a minimum of 1 hour of playing the dozen or so genres that I listen to regularly (Prog rock, Rap, Acid Jazz, Classical, Techno, Rock and Roll, Blues, Trip hop, Reggae, Dub, PsyTrance and Pop) and at volume levels that most people selling their speakers are not comfortable demoing the speakers at.
So, while testing at someone's house is useful, it is by no means the only tool for shopping for speakers,
which is why I love asking you guys questions!
It seems like maybe I should be more patient on the JBLs. It seems there are more highly regarded ones out there, and the particular pair I'm looking at now, while rated a 9/10 on appearance, they are quite pricey. About 20X what I paid for my CVs. I can't imagine they are 20X better.