Well recorded audience noise is one of the best things about live recordings, being able to place each sniffle and clink of a glass is a great test of verisimilitude. For example, a visitor brought round a live Horowitz CD yesterday and I really enjoyed teasing out the differences between creaking chairs and the noise of the piano action. For me it's these idiosyncrasies and "faults" in a recording that make this hobby real and why I often prefer live versions to the studio originals