I spend a lot of time thinking about description - because I'm so bad at it. Particularly "sensory" description, since I am a visual person. Even for a human, I have a poor sense of smell. Really, there is just so much going on in my head all the time, I'm not always aware of noise around me.
Think about it: When you are in any situation, do you notice (as many fictional characters seem to) what you see, smell, hear, taste, feel? I mean, all of it? Maybe it's true of mystery or detective-type people or characters because they are trained to or just naturally pay attention to everything.
I feel people are more like me: Sometimes, I may walk into a room and notice that it's cold or quiet or smells really bad. Often, whatever strikes me most or strongest gets and holds my attention. I don't immediately think, "There's an awful smell in here", and start focusing on what the room looks or feels or sounds like. It is true (especially in fiction) that on occasion a person might walk into a place that is dark and cold and smells bad and is either freakishly quiet or overwhelmingly loud and make note of all these facts. But not always.
Anyway, I generally only notice what I see and sometimes can't focus on that enough to be able to describe it later. So that's how I write my characters. They mostly only notice how something looks, but not always, and rarely anything else unless it's something out of the ordinary.
However, I do appreciate good description and try to learn from writers who have a gift for it. I am envious of authors who can use simple, powerful descriptions.
For example, one of my favorite descriptive phrases is from a Sookie Stackhouse novel (Southern Vampire Series) by Charlaine Harris. Sookie comes across her ex-boyfriend, Bill, who has been tied up and tortured. As I remember, aside from mentioning that he's been grievously hurt, she didn't detail all his injuries or describe how he looked. She noted, "He had one unbroken finger" (that he used to point with). Just from those five words, any reader with imagination will suffer mental images of what else might have been done to Bill.
You would think - at least I would think (or hope) - since I can only focus on one thing at a time, that I would be able to describe at least that one thing well. Or, even better, concisely. Unfortunately, I can't. Yet. It is just another of the many things I continually strive to improve in my writing.