Look up at the ceiling tiles for stained spots from old neon signs or water damage that tells a story. Music stores had listening stations, so check for weird floor outlets or bolted-down platform bits everyone forgot. Smell can be huge too - that mix of dust and old carpet is totally different from the plastic scent of new CDs back in the day. Notice how your footsteps echo now versus the muffled sound when the place was full of people and racks.