For a site that puts so much emphasis on including permission on works of others that you have used as a basis for your own creations, there are still skins getting on that should never have made it past the moderators if they had checked. I'd like to say "more thoroughly" but obviously "not at all" is what happens far too often.
There is a logon that's been up for 2 weeks now, using a wall from one of the better known wallpaper artists here, that simply says "Thanx for the permission, man" with no permission included. He says he forgot, would put it in, and never did. The person who made the wall says he doesn't even know the guy. Yet, on my last logon using this persons work, (which I have exclusive permission to use), I get a comment from administration making sure to put in the description that permission is included, which of course it is. Yet this other total rip remains on the site with no permission at all.
And the wallpaper library, supposedly the one most heavily moderated, allows a wall using an icon from another artist on this site without the artists permission, the person then adds a thanks and a link to the author's site, but no permission included in the file.
I can see this happening perhaps on things that aren't very obvious, getting missed, but there seem to be a lot of examples of this happening with work that should be known to the moderators and checked for permission. They should be some of the most knowledgeable people here with knowledge about what is getting submitted.