First: Sorry if it isn't allowed for a normal member to reply here.
Well, I wouldn't call myself an expert but the scan in your wallpaper is much more than just blurry. It's grainy and
have a lot of jpeg artifacts covering it. Short said: poor quality.
You can best see that in the face of the girl sitting around her mouth. I think even you must admit that this is not a
very clean scan but taking a closer look. The bigger scan is also very blurry.
Aside from the facts above your wallpaper is very plain.
I don't wanna sound harsh but it's just two scans slapped on a black background. That's not really a wallpaper. A
wallpaper needs much more work. You need to create something like some sort of scene you want to show. The background
should work with the scan you choose to make a wallpaper and have some kind of relation to it.
That's my two cents about your issue and I'm more than sure that the mods here will agree.
Good luck with your future submissions.