I became curious, as I hadn't seen these submissions....
LogonXP is actually MORE than plonking some wall image 'found' somewhere on it as a background, there's actually other 'bits' to skin.
Each of these submissions was specifically poor, irrespective of whether the source of the image and its use was approved or not.
Images 'found on the net' are almost always freely available for PERSONAL use. That means you the downloader are free to use it/them on your desktop as wallpapers/whatever.
Almost NEVER is free consent granted to publicly redistribute in any form what-so-ever, certainly not without a process of formal request/approval, or at least the inclusion of 'included copyright' from the source indicating such.
These Logons failed on both counts - quality AND consent.
There are other sites where you 'may' be able to upload/display/distribute these, however no matter where you are still violating the original artists'/photographers' copyright.... and yes, it IS YOUR job to seek/obtain consent to use/distribute. IF it's 'hard work' well, that's life.