Can the absent-minded be rehabilitated?

I’m not sure if I even mean absent-minded—I’m talking about the kind of person who doesn’t notice things that are right in front of them, doesn’t pick up on clutter until it’s a disaster, that sort of thing.

This seems to be a character trait that a lot of people have. I don’t think it’s the same as laziness and I don’t think it’s terrible, but I’m wondering if it’s a stable trait or something that can be modified with effort.

The specific behavior I was thinking about has to do with cleanliness. I now live with someone who seems to be incapable of putting trash in the trash, even when the trash can is right there, and the trash object is clearly trash. I am constantly throwing away or recycling wrappers, old receipts, empty bottles, etc. It’s not a big deal and I don’t mind doing it, but I’m wondering if I make a habit of pointing out trash that can go in the trash, if the offender will learn and modify his behavior, or if I’m wasting my time and I should just accept my role as the trash-thrower-outer.

Have you become more or less conscientious over your life? Can you learn to notice things that you normally wouldn’t notice?