Hate to say this but I disagree, you might be able to eliminate some if they're particulary sharp or something that really stands out you don't like, but one of the biggest influences on overall sound is the room and hence why some people spend as much .... if not more on room treatment.
I've been and demo'd speakers that came across bordering on boomy in the demo room. As I'd driven there thought I'd take them home and try then anyway, in my room the kick drum sounded amazing, it was like you were right next to it, but the range between that and the mids was totally lacking.
I also think "fatigue" can set in which you'll only notice after a while, I bought a pair of ex demo speakers and it was 2 months later I sold them as I realised a long listening session with female vocals got to the stage you just didn't want to listen anymore.
If people can make an accurate assesment after a 30 mimute trial in a treated demo room and be 100% happy with them 2 weeks after they've got them home, I take my hat off to them but personally I like a longer home trial.
Not a crticism of anybody else's thoughts, just my own personal thoughts / experience.
