I've been thinking a lot about this, as you probably realize. And here's another way you can look at it. When you go into someone's house for the first time, how much do you learn about them from even a first cursory look around? A lot. I'll use my own house as an example.
First, the outside. It's a small house, wooden, around about the same age and design as the rest of the houses on the street. The paint is faded and peeling in places, but not enough to look derelict... yet. The garden is overgrown and weeds choke the flowerbeds at the front. Whoever lives here doesn't do much in the way of gardening.
As soon as you walk through the front door, you'll see toys or kids' shoes strewn across the hallway. So there is at least one kid living here. The hallway has bookshelves in three places,two crammed with children's picture books and the other filled with non-fiction books about writing, motor racing and the technical side of recording music.
Bedrooms branch off the hallway. Two belong to kids, toys dropped carelessly on the floor, pictures on the walls of cartoon characters and fighter planes. Probably boys. The third bedroom has a double bed - the parents' room. Clothes lie around in sloppy piles and there is a stack of clean laundry stacked on the bed. The people who live here aren't that fussed about housekeeping.
In the living room, a large television sits at one end. Nearby is an impressive collection of DVDs and racks and racks of CDs. These people are serious about movies and music. More toys in this room too. The furniture is baggy and a little stained, definitely not new. Crumbs litter the rug under the coffee table. They probably eat in front of the TV.
In the dining room sits a table, lost under piles of mail, newspapers and other stuff. Doubt the family eats there. Only room for one person to sit and eat, at the end. A small plastic table sits across the room, next to two floor to ceiling bookshelves jammed with books on film and music, plus an eccentric selection of novels, biographies and short story collections. These people are definitely interested in film and music.
The kitchen is surprisingly clean. They may be messy, but not unclean. Appliances litter the bench and a large collection of cookbooks is piled on a shelf. More recipies, torn from magazines or scrawled on pieces of paper, are stuck to the fridge with magnets. Someone likes to cook. Closer inspection reveals most of the recipies and cookbooks are vegetarian. At least one person here is a vegetarian, or at least, they want to eat more vegetarian food.
In the bathroom, an empty teacup sits on the edge of the bath, an open book facedown beside it. Someone likes reading in the bath. A few bath toys are scattered around the rim. The kids are still young.
And that's just a very quick walk through, glancing around. If you look closer, read the paper pinned to the noticeboard by the front door, study the papers left on the table or by the computers, you'd learn a lot more. These small details can be thrown into your writing, showing the reader what kind of people live in the house rather than having to tell us through narration, or dialogue that may not advance the plot. By describing the house, you're not only giving valuable character information, you're also grounding the reader in the environment your story takes place in.
Assuming of course, your story or scene takes place in a house. But the same concept applies to any setting whether it's a space craft in some unheard of galaxy or a shack in the middle of a fairy tale forest.