Are there people who could careless about decorations for their home?

Yes. Usually I’d find this in an apartment where they’re only temporarily staying there, so they don’t want to waste money/effort on decorating, or they can’t paint, etc.
But there are houses where people just have the fundamentals — the couch, the TV, the bed in the bedroom, and don’t care if the furniture matches or what, not much on the walls, no personality. I think these people just don’t care about decorating, or they don’t KNOW what to do with it, so they leave it "undecided."
They may also have more interest in other things outside the home — they may hardly spend time at home, and they may not put their money into decorating.

Sure, but what you’re really asking is if there are people who "COULDN’T" care less. This is a common grammatical error. If they "could" care less, that means they care more.

Oh yeah! I’ve been in people’s homes that were devoid of decoration, accessories, paint and looked like a mid-level hotel room stuck in the 80′s. There was absolutely no sign of life, no indication of the people who lived there, who they were, where they had been, what they had accomplished or any reflection of their personalities whatsoever.

Sure, poor people who need that money for food.

Yes, I know someone who has a house exactly like that, but he’s no longer with his wife, travels extensively on business, and claims that art "Doesn’t speak to him." *shrug*

Yes, of course. In fact, MOST people could care less (it’s two words) about decorating their home.

Since most people DO care a great deal, or at least SOME (or they wouldn’t decorate at all), of COURSE they could care LESS.

You have to care some amount before you can care less.

There are also a very few people who do not care at ALL, so these people could NOT care less.