I am not a maid and I think about the issue with common sense. Most clubs and restaurants need to hide the dirt for a high maintenance bathroom. vomitings along the sink are common in clubs and stones were often employed as back splash for that purpose.
Dark slate tiles also hide a lot of dirt as well. The health and safety code only govern the the detail for the flooring transitioning to the vertical wall surface along the base of the wall. It must not be a crisp 90 degree corner where baterias and germs could live in the tight crevice and mopping it is difficult. All public bathrooms are required to have a cove (1/4 round) vinyl base or a piece of curve tile to soften the 90 degree transition for easy cleaning.
Other than that any material could be employed for the wall and flooring material.
Higher end hotels often use a very light color marble or polished lime stone palette and white linens so the patrons could examine the premise for their cleaniness. The lower chain motels re-use busy floral pattern comforters and faux granite pattern formica to hide stains.
Finally, homeowners like the trendy use of stone at clubs and restaurants and incorporate them into their custom remodel.
[quote author="anela" date=1209553723]bk, when i first saw all the stone in those bathrooms the first thing i thought of was "how are you ever gonna clean it". one of my first jobs was as a maid at a hotel and i look at things a little differently than most - it doesn't matter if it's a floor covering, countertop, cabinet face, moulding, sink, a piece of furniture - it has to pass the "easy to clean" test. also, the bathrooms seem rather cave-ish with all that stone. glass sinks look pretty in pictures but don't look so good if you don't wipe them down after each hand wash or tooth brushing
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