At the end of the day nobody cares if you make the best mix in the world. 99.99% of listeners don't even know what they're hearing half the time. We do this for personal satisfaction, but it HAS to be tempered at some point by restrictions imposed by reality. You have to eat - you cannot offer free studio time forever, nor mix the same track for months on end. We're subject to dealing with less than ideal circumstances, that's just a facet of the job.
I would say your clients do, and discriminating clients who are looking for the best AND have money to spend are definitely swayed by the obvious quality of an engineer's work. If your mixes rule, and the songs sound great, you're getting business. Most great bands are willing to spend money to better their release, and if they don't the first time, when they do an album with someone else that sounds lackluster and realize you would have done better, they would go to you.
I agree that the listeners don't have a fucking idea what is going on, but you have to consider this:
-Good mixes don't sell albums; "good songs" do
-The guitar/bass/drum tone =/= a reason to purchase an album
-"Popular" or "Professional" bands, no matter how shitty they really are, who sell tons of albums, are selling a ridiculous amount of albums for some reason or another
-Bands are egomaniacs in most cases; they want their record to sound stellar, they want it to be competitive. They want their music "painted" the right way by their engineer.
-Connecting with the band as an engineer both on a personal level and a professional one is going to make your clients happy
-Happy clients talk about your services
-When other bands hear the material you have done one previous projects and are stunned by the quality they will go to you
-Providing the best for your customers will get you THE BEST customers
-You are now working with more popular acts who sell more albums
-Your work is now featured on albums that have sold thousands of copies
-Things have come full circle, and your work has been showcased
I know you have to eat, but you can still stay up a lot later than you should making more edits, tweaking levels, etc. It's really about the drive that you have that will shine in everything that you do in life, not just audio engineering.
I think it all makes sense, and I don't really have any "bullets" that are out of line. I'd say everything is word of mouth and the finished product. I never once thought in my life I'd worth with a band that Jesse Leach or Marco Minnemann was in, and I definitely didn't think that I would have the pleasure of working with both groups potentially TWO times.
Now, you do audio engineering full time. I don't, but I do plan on it one day. Your "experiences" are definitely more valid than my "models for experience," but I can say that I've learned a lot in the short time I've been doing this stuff.