Actually, I do rent out my audio room. I have a couple of recording studios that use it to proof their master CDs before going to print. In almost every case, they have found something wrong with their CD that they did not hear on their own setup.
The whole trick is making sure your system (room, speakers, amps, cables, etc.) is much better than what they have. It is actually not too hard finding better speakers or amps than most of the recording studios but it often is extremely hard making sure your room is better than theirs. For me to reproduce my room somewhere else (like in an office space), my estimate is that it would cost somewhere in the neighborhood of $60k (that is strictly for the room remodeling and acoustical treatment, not the stuff that goes in it like speakers, amps, etc.). The start-up cost makes it totally impractical for most people but works in my special case.