Smell is another one. And neither sound or smell can be accurately measured in any everyday way. (As opposed to people with special equipment.)
I really don’t like places that use those cloyingly sweet air fresheners but many people don’t mind them at all showing once again that everyone is different.
Yes, noise is very tricky. I had a guest once who got in touch before he booked. (I use IB so this was unusual). I forget his reason, but he said that quiet was essential as he slept (or worked, I forget) during the day.
I had to tell him that although I consider this place to be very very very quiet, I can’t guarantee that a neighbour’s noisy lawn service won’t appear one afternoon or that a very noisy cigarette boat with thrurpy engines won’t zoom up and down the canal one day - something that has only happened once or twice in years but it would be just my luck…
I’m glad I told him, and he didn’t book, because all the time during his stay I’d be on pins listening out for the slightest noise - a rustle of leaves, a mouse sneaking by … 