I recently upgraded my headphones to a model that is much more clear and analytical than my previous cans. It was such a significant boost in those categories that after a week of intense listening, I can pretty much tell whether an audio file is or is not in a lossless format where as I couldn't before.
 
But something I noticed has made me extremely disappointed. Most of my physical CD collection, I have found, is really terribly produced! All Metallica albums pre black album, Rolling Stones 40 licks, Led Zeppelin, if you had me do a blind sound test I would probably categorize the albums as low bitrate files!
 
And in a rather weird twist, when I tested my new headphones I tried to listen to as many genres as I could so I set iTunes radio to smooth jazz and country stations, genres I don't normally listen to. Lo and behold, the vast majority of the songs on the stations for those genres sound MUCH better in terms of SQ and production values. Even sampling some Dave Brubeck from the 60's sounded better produced than my physical classic rock albums from the same time period. And these were, at best, streaming MP3s.
 
So have any of you noticed anything similar? If so, what gives? Do you feel that there are certain genres of music that are consistently produced with higher production values than more mainstream fare?

Contemporary jazz.  Always top notch.

Pop vocals and jazz vocals from the 50s and 60s (Sinatra, Ella, etc.), early stereo era Jazz, just about any classical music since the introduction of stereo. A few rock artists (Steely Dan, Joni Mitchell, Ry Cooder). Recent bluegrass. 60s easy listening (Mancini, exotica, etc.)

Electronic music most definitely. A few examples. Nu-Disco: http://m.soundcloud.com/televisormusic/televisor-life-out-now-on
Chillstep: http://m.soundcloud.com/moxix/1point5-ft-al-rolfe-upsanddowns Hardstyle: http://m.soundcloud.com/moxix/rage-free Orchestral Progstep: (that's what Omnitica called it at least... He also has a song called I call it progstep.) http://m.soundcloud.com/omnitica/straw-hat-pirates-instrumental

And whoever mastered for def Leppard actually was pretty good at it albeit being an 80's rock band. I also like Guns N' Roses. Their songs are pretty well mastered too. The eagles are well mastered imo, and so is jimmy Buffett...