Condo builder on record wants to check my condo loft (2nd and 3rd floors) for smells in 1st floor business below (parking garage in basement below that).

I don't see why - I have no smells in my unit and all walls are enclosed in drywall. I have one and one-half baths - I use all facilities regularly including laundry. And also kitchen sink.

I think this request is unreasonable.

I think your builder better stick to the lower floors and have a peppermint or a smoke test done on the system, Sewer gas will raise in hot weather and fall in cold. Let me know what he finds, Good luck, Tom