What exactly is critical listening? Who does it?

Suppose I want to compare the sound of the same radio program via streamer/DAC vs. broadcast (FM tuner). I simply switch between input X and input Y on the preamp. That's an example of critical listening, and it's neither nonsense nor self-flattery. Or I want to compare the sound of preamp A vs. preamp B into the same amp (one on balanced, the other on RCA). Just switch between the two inputs by pushing button on front panel of amp. That's another example of critical listening, and a useful one. The list of potential listening tests is pretty much limitless, but of course, once satisfied, we lean back and enjoy until some other aspect of the system warrants our critical attention.

To me critical listening is focusing on things like sound staging, pinpoint image location, and all the other esoteric things that a typical audiophile cares about.  Casual listening is not focusing on that but more so just enjoying the music.

If you are focused solely on listening you are listening critically. The more distraction the less critical the listening.  

Critical listening is done in order to attempt to get the sound of your system to sound as good as possible to your ears. Once you're done with the room soundproofing and acoustic treatments, then come the equipment upgrades and only then you finalize it with subtle sound changes with various cables, fuses and isolation products. Each one of those changes will easily be noticeable and that's when critical listening is absolutely necessary. The hope is that eventually you never need any more critical listening. Audio nirvana. Am I there? No. Am I close? Definitely. It's a journey, just like the spiritual one.

@mapman +1 This is more what critical listening means for me, critical listening is listening with great intention, again, critical doesn't mean judgement. On the other hand, analytical listening mode is intentionally judgemental, you are listening specifically for qualities of sound rather than sound quality. Critical listening should bring about appreciation for sound quality, I go into virtually every listening session with great intention for appreciation of sound quality, I donj't listen to my main system casually. Now sometimes during these critical listening sessions I may hear something in certain recordings that is salient to the point it brings about an intention to analyze.

After decades of practice/experience I'm always aware of the listening mode I'm in. Critical mode is my favorite mode, again, this is not a judgemental mode. At this point in my audio journey I'm never in pure music appreciation mode when I listen to my audiophile system. Per the above I'm mostly in critical listening mode, this is intentionally an appreciation for both the sound quality of my system and the performance of the musicians. And this is also necessarily an appreciation for the engineering/production values of the recording, something that seems to be completely forgotten in this discussion. The kind of appreciation I'm speaking of here is non judgmental so that recordings with flaws can  be enjoyable. 

Bottom line, I'd find this entire endeavor intolerable if I couldn't listen with great intent and non judgment  to the musical performance, sound quality of both my system and the recording, perfection rarely if ever exists, flaws are ever existent  I submit the entire reason I got into this was to have appreciation of all three of these aspects of listening to recordings on an audiophile system. If I'm only seeking musical enjoyment I can find that easily enough with relatively low end systems such as in my cars or work system, with these systems I care little about system and recording sound quality. My take is if you're not listening to your system critically, something in the system isn't aligned with your sound preferences and/or pales in comparison to some reference system you heard or have illusions about.