How do you judge audio components and speakers?

I would say - listening to music you're familiar with, and comparing. We can talk about tight/bloomy bass, midrange clarity, treble extension and things of that nature. We can also be very specific with regards to how a particular track is supposed to sound; based on high-performance gear that we were able to experience - but only if it purports to be accurate without sonic colorations. Therefore, I guess you could say we have a reference point. This part is what I would consider "objective performance." 

Along with this, measurements go hand-in-hand.

On the other side of the coin - subjective performance is how we "want our systems to sound." If the vocals are too bright or sharp, if snares or unpleasant sounding instrumentals ruin an otherwise good song, it's usually because the system is too accurate. So high-end audio is about chasing an ideal that doesn't exist in reality - but in the minds of audiophiles who are seeking a very particular kind of sonic presentation that bodes well with their music library as a whole....giving you just enough detail to keep you interested, while at the same time having a sense of realism, presence, and imaging that makes the speakers dissapear. We are seeking the illusion of a live performance.

The above are just my points. Feel free to share what you think. If you think I'm wrong, I don't mind. 

Cheers.

Jack