Used one in an open office plan with 6 people within about 10 feet and never had any complaints.
I'm almost certain they pumped white noise in though. It was never confirmed, but one day it was oddly louder and everyone noticed...
Either way, I think the deep thock is generally less noticeable than other switches. No one ever mentioned my HHKB, but everyone would remember the cherry reds a coworker used, although he did type like a baboon.