Addendum:
The final section of the first sentence in the last paragraph of my above post (phew ;-) reads "made to simulate live music." I was of course referring to instances where that was the actual intent of the producer (and perhaps artist/band). Far more common is a very different intent:
During the playback of a track (whether in recording or mixing), the engineer will run his tape, A/B-ing the sound with that of a current best-selling song. He then manipulates the sound of his recording with a number of pieces of outboard gear (and of course his mixing board), all in his attempt to make the recording sound as much like a current hot song or album as possible. No references to the sound of live music at all, purely subjective.