Sharing the floor means sharing some other spaces as well. One would be the small sink and wash up space and the other major shared space is the toilets. Again, this is not really any problem since they seem to consist of a regular boring bunch of salarymen of reasonable hygiene who are not punishing the toilets with more wear and tear than the cleaning staff can handle.
There is one issue though... I strongly suspect that a few people among our neighborhood companies are systematically taking post-lunch naps in the toilet booths. I can understand that the pressure on the toilets get a bit higher post-lunch, but every day from 1-3 pm the booths are chronically occupied... Once, when the need was quite pressing, I actually waited outside the booths for around 5 minutes in the hope of an opening but no luck. During my wait, no sound was heard from the booths, none of the regular natural bodily sounds, tearing of toilet paper and spinning of rolls or flushing. Just complete silence.