After reading some responses, some more thoughts:
Like most, experience is a key factor in telling differences in files. If you have read/experimented a little, you may know some of the usual flaws of lossy files - watery cymbals, smeared instruments. But one thing that baffles me is that in these tests, the factor of familiarity is never considered. Let me explain what I mean:
I like steak, generally cooked medium. But I know when it's undercooked, or overcooked. All the music I know and love is my steak.
Now, someone serves three plates of Dodo meat, and asks me to say which is overcooked, undercooked, or just right. What???
I can use the principles of my previous experience to try to tell, but such as I have experienced before may not be present - thus I fail the test.
It amuses me to think about creating some music which would purposefully sound liquidy and smeared, and which perhaps could somehow "clean up" with the linearization of lower bitrate! Experts would be baffled at realizing the "worse - sounding" file is the most correct one...
If I don't know exactly how a file is *supposed* to sound, I can't really be expected to know which one is more correct. One is more readily able to tell quality differences when one has a baseline, I believe. I seriously think tests results would be quite a bit different with songs "everyone" knows...
And this is without going into the details of music which may not be losing that much even when coded into lossy format... can the listener then be blamed? I saw one such test online a while ago, trying to prove no one could figure out where a file was lossy or lossless, and it proves nothing, in my view... I did a brief comparison of Morbid Angel's Covenant album 320 and FLAC, which I know well, and to my surprise the difference was fairly obvious - other more complex extreme metal is even more abhorrent of lossy files. I have likewise been surprised at how good some 192 kbps music has sounded too.
Oh, I also forgot to mention I have tinnitus and hearing loss of higher frequencies in my right ear... and apparently I can still tell differences in SQ.
Just some cents... Cheers, everyone.