There's at least one episode* where we see a Starfleet officer with a messy cabin, too, so I suspect the computer/drone setup doesn't actually clean people's personal quarters. Which is probably just as well, as a gesture to encourage self-discipline among the crew.
*(The one where a woman in engineering falls in love with Data, then falls right back out of love upon realizing that he is, in point of fact, Data
![Razz :P](./images/smilies/icon_razz.gif)