Critical oppositions made using inadequate equipment.

Oppositions aside, most wouldn't know the difference. 

Loudspeakers in an infinite variety of rooms are so varied that evaluating other equipment only has merit in a particular system. There are exceptions, a cartridge that does not track well will break up prematurely and that will apply to all systems. Otherwise clearthinker is right, you can not generalize to other systems. Now if there was a calibration standard that could be applied to audio systems like there is for projectors this could change. This is actually now possible given digital control but would not apply to "analog only" individuals. 
In short, we are very much all alone by ourselves when it comes to evaluating equipment. What sounds great in your system may not be great in others regardless of quality. This is one reason you have to take reviews with a grain of salt. You may also notice that certain brands are always being reviewed by people who are fond of that brand to begin with. Bias has many forms. 
How do you keep from buying equipment that will not work well in your system? In the end you can't. I would bet that many if not most of us have bought equipment we became unhappy with. Our systems evolve slowly over time and we learn what works well with our own situation. Set amps will be worse than terrible with my speakers. I know not to go there. With horn speakers my amps are extreme overkill. There are so many ways to skin this cat. We all have our own ideas of what is best. I do find it interesting that if you have an excellent system evaluated by a number of audiophiles all will agree that it is a fine system. The same will happen with a terrible system. All will agree it is terrible. So there is a standard in our heads even if you can't define it.  

@tomwh, your first two paragraphs are very true. A great system has to be able to mimic all these genres and venues with authority. But I respectfully disagree on the overriding importance of the midrange. If you want the live experience the entire audio band from 18 Hz to 16 kHz is important. Certainly, if you have to settle for a limited system the last thing you can compromise is the midrange. But, for the live experience it all has to be there especially the bass. 

Quads were special because they were the first speaker that gave us a hint of what was possible. But, they then developed the speaker in the wrong direction trying to improve it's performance as a point source speaker instead of evolving towards a full range line source. The Europeans are more concerned about size than Americans as many more of them live in places with limited space. 

@ghdprentice , Really? Last night I saw The Tower Of Power in Hampten, NH at the Casino Ballroom. The band was phenomenal but the sound system SUCKED!! There was distortion behind the singer's voice but not the horns, maybe a bad mic. There was a lot of sibilance which made me squint once in a while. It was a mono system. The bass player was buried behind the bass drum which BOOMED. In short, the three live records of theirs are superior in every way. The individual instruments are beautifully outlines. I can match the level without any stress or sibilance and I can clearly here each bass note. The bass drum thuds with assurance. 
Certainly, people who have been to indoor stadium concerts will tell you the same thing. If you can get a good live recording the sound can be much better at home. If you want to compare your system to the real thing than any acoustic setting will do, classical, folk or Jazz. Electrified bands that are playing through their own amps Like the David Holland Quartet are also great especially if they keep the same set up on their live recordings. Very Cool. Now, what were you saying ghd?

tomwh, What Do You Want From Life?  Yes, I like bass very much and I like midrange and treble. As I explained above there are many instances were a recording is subjectively better sound than the live event. But there is only one live just like there is only one right color calibration for projectors. Having measured several systems besides my own I can guarantee that the majority of systems/rooms are not properly calibrated. Some of them are way out with 10 dB and over deviations from flat even up high. Not only that but the frequency response of the left and right main speakers can differ by 10 dB.  The colors are way off. Most of this can be easily fixed with the right equipment all of which operates in digital. This is a leap analog folks are scared of making. If you like vintage sound go for it but, that is not where accurate reproduction lies. There are certain things that have to be done like getting the sound balance/tonality that you like, adjust the response of the individual loud speakers so that they are within 1 dB of each other from 100 Hz to 12 even 16 kHz, Create a two way cross over for subwoofers with a 48 dB/oct roll off and match them with the main speakers in time and phase, create a brick wall rumble filter that drops at 80 dB/oct from 18 Hz and finally Boost the very low bass +6 dB at 20 Hz. This gives you that live feeling at slightly less than ear shattering volumes. 
People laugh a this approach but some of you know better. How do you know that a system is too bright if you don't know what flat sounds like?
It gets back to that calibration thing. You have to calibrate your brain. Experience is the best teacher.