What exactly is critical listening? Who does it?

I always listen critically because I want to know what the system is doing well, what could use improvement, and maybe most importantly, what the engineer is trying to convey (and maybe not convey?).

I want to hear all those small changes that would go unnoticed to most.

I want to hear the engineer "touch" the pan pot.

When a singer doubles their voice, barely audibly, in the background, I want to be able to hear that for what it is, and where it is.

On overdubs, I want to hear the "punch in" when it occurs.

I want to hear the buzz of the amps from the performance, though I could do without the snare rattle.

I want to hear when the noise gate opens and closes.

I want to hear the "easter eggs" many of which will never be picked up through casual listening on a lesser system.

The list goes on, but these are the things that I find enjoyable and keep the music fresh and most are only picked up through critical listening.

BTW, if it matters, I am a retired consultant/scientist who specialized in noise and air quality studies for CEQA compliance.

Critical listening is the gateway to whatever is there on the other side of the fence.

Of course I’m going to critically evaluate components that I’m spending decent money on, and then when it comes through the door I’m gonna be very critical to ensure it does everything I was hoping for.

I’m gonna listen to all kinds of music that I’m familiar with critically evaluating the changes and hope to be hearing with a new purchase.

When I was younger, I never had the awareness to listen very very carefully however I was very mindful of how well music filled the room vs crappier systems which were disappointing.  

I think you can balance critical listening and other types of enjoyment at the same time.  Unfortunately, we all have an instilled discipline within us that prevents us from avoiding this ongoing critique of everything we do and see. 

Presently, I’m done buying all this audio stuff aside from potentially upgrading speakers. So the critical side of the mission is fading away, thankfully.  Maybe I have to buy a car and I have to now critically evaluate all the new electronics and stupid digitized Dashboard which is horrifying, I don’t like a having an iPad embedded in the dashboard. 

I'd suggest critical listening can be broken down into two sub modes, one judgemental, the other not. Judgmental mode is for evaluation, listening to sound quality, qualities in order to compare, contrast to some reference.  The other mode of critical listening is intentionally careful listening which should bring about a sense of heightened consciousness in which music, artistic performance and sound quality, qualities all serve to maintain undivided attention to this single activity of listening to music on a high end system. Music, artistic performance and sound quality should all have great salience such there should be a conscious acknowledgment and appreciation for each.

When I was younger, I never had the awareness to listen very very carefully however I was very mindful of how well music filled the room vs crappier systems which were disappointing.  

By 'younger', are you referring to your days in the first grade when you were checking out different power conditioners?

@immatthewj 

way earlier.