The thing about hearing a difference between gear is that not everyone listens for the same thing. When Head Fi member
romaz took part in
Tyll's Big Sound 2015 he was basically the only one who could pass the blind tests (He's a physician, well educated, well spoken, and has a scientific mind). When asked how he did it I believe he said in the forums he listens for the sense of stage in the music. Once he locked on to that it was fairly easy for him to differentiate between gear. Of course I'm paraphrasing, but the point is that if just listening to the music as a general whole then one may not hear any difference at all between gear. Also, the entire chain plays a large part in being able to hear audible differences. With a sub-par transducer the source gear differences will be further masked in distortions and frequency imbalances.
Some members listen to certain things that they find of great value and therefore, to them, the differences are 'night and day'. Others simply don't care about listening for the same things so they will never 'hear' a 'night and day' difference. I think that's where the majority of disconnect happens in describing audio and audio gear.
While there is definitely an audible influence from different individual anatomy I'm pretty sure there is not an audio equivalent of colour blindness (where 4kHz would sound like 30Hz, for example), so I feel, as a whole, we pretty much all hear sound as we should within our individual hearing ability. Continuing with the hearing / sight comparison, our brain filters out a lot of information we gather from our eyes and it processes the result to create a mental image of what we 'see'. I'm pretty sure our auditory system is the same and it's the brain that ends up separating what is the same or different relative to what it has 'heard' in the past. Because of this, if the brain isn't focusing on a certain aspect of the sound, or doesn't value a certain aspect, then the differences 'heard' will not really be evident to the brain IMHO.
With the Mojo, to me, the differences were immediately evident from the gear I owned when I first heard it. Even more so the longer I acclimated to the sound. When a reviewer simply dismisses a difference in sound that
I clearly hear then I just chalk it up to the reviewer being lazy, or simply not focusing on the same qualities that I do.
Of course this doesn't apply to everything as some gear simply does sound the same/similar. Also, it's all relative to the experience of the listener and the qualities the listener values/focuses on. As it says in my signature... If it produces pleasure for the individual, then it's right.