I think a large measure of this is having a maid... not in the obvious sense, though.
Since I hired a maid, I find myself much less likely to keep things cluttered. On the one hand I sort of feel "bad" messing up the house, and on the other hand I know if I clutter things up it makes her job harder and irritates her
It's funny, in a way... having a maid at times makes ME feel like "the guest": she has her little flourished and way of doing things (for example, she arranges a tissue in a sort of origami rosette atop all the tissue boxes in the bathrooms, and she folds the towels in a certain complex, decorative way). I'll even sometimes reposition a statue or something, only to discover later that she's put it back in the "right place".
Now, I'm a complete pushover, obviously, but I suspect that wealthy folk are often somewhat beholden to their staff, in the same way we often are to our assistants (anyone who has ever had a really competent executive or personal assistant knows that sometimes it feels like they're more boss than employee).
Certainly I don't dare clutter *her* house!