About Eli's way of dressing...

[Imnotazombie]

I think it's because Eli just didn't give a fuck. He had no one he really cared to please, and that's why he starts dressing better when Oskar comes along.

[metoo]

... He had no one he really cared to please, ...

Not even himself...

[JGrayzz]

I'm not going to go out on a limb and say I dress in raggedy, hobo-ish clothes because I don't. However, personally, I like to wear sweats and "baggy" clothes simply because they are comfortable and they are just that--clothes; besides work and "special" outings; clothing style isn't a priority. Eli appears to have a more extreme sense of this mind-set; she wore clothes because she had to and style wasn't even a thought. Survival is the top priority.

Then Oskar came along....

[Luftwaffles]

I think it pretty much falls into the "otherness" of Eli. I think that's part of the "statement" (if there is one) that the author makes about the character/situation. It's symbolic of her otherness. If you'll notice, when she is at the pool looking in at the window (blammo symbol) and Eli is wearing normal people clothes, it just kinda illustrates her shortcomings of not being part of that world -it's not the clothes that make her a part of it, it's her essential "Eli-ness" that refuses to let her participate in that world. Cause even tho she's dressed warm ("I guess I forgot [how to be cold]"), she's still not gonna be able to participate in Oskar's world.

[Luftwaffles]

Also

GO TEAM ELI