An excerpt from the upload guidelines (https://www.wincustomize.com/guidelines.asp)

WALLPAPER MODERATION:
Typically, only the wallapaper section is moderated for quality, but it is difficult to be specific about the moderation process. Lets just say that a lot of submissions don't make it in. The wallpaper section at wincustomize has grown faster than we expected and we are trying to hold it to a reasonable number of offerings. To accomplish this we are being very selective about the artwork that remains in the database.

The last thing any of us would want to do is discourage an artist from uploading their work. All of us are involved in making digital art and we are all committed to seeing the popularity and availability grow.

Our guidelines for judging wallpapers on aesthetic grounds are difficult to be specific about. The prime directive for wallpapers is that they must WORK as a wallpaper, in other words the design should be an effective desktop background, which includes: The background is not too busy and icons are easy to see against it, Colors are not too bright to be distracting, and colors work well together. There are many subjective design related preferences we all have and some objective qualifications as well, such as the quality of the rendering and the resolution size offered. And then there is the composition, the subject matter, the overall balance of the design, etc.

Probably the best way to decide what we like to see in a wallpaper would be to browse through the section and look at what has been accepted. We recommend to everyone submitting wallpapers to try to only send a piece after living with it on their own desktop for a while first. Put as much work and critical evaluation into the piece as you can before sending it to us.

A few examples of what will never get through moderation:
- Britney Spears or other celebrity wallpapers (see note about copyright above)
- Bryce art, unless the result is so astonishing that one could never tell it was done in Bryce.
- Dolphins, palm trees, metal spheres or other over-used elements
- XP-related walls, unless really innovative/original.
- Copyrighted photos/images
- Confused composition...eg...3D artwork with conflicting light-sources belying the form.
- A ground-swell of negativity from a significant number of admins.