'Ripping' is merely a trendy term to refer to 'copyright theft'.
The publication, or re-distribution of another's artwork in part, or in whole, without the original author's express permission.
It most commonly refers to people who deliberately plagiarize, copy, steal another's work to claim credit for themselves.
Some people mistakenly assume that posting a credit to the original author will suffice.
It does not.
When an artist publishes a work, in this case, uploads a skin, wall, or theme to a web site such as this, he/she does so with the intention that his/her work will be downloaded and used [even altered for use] PRIVATELY by the downloaders.
At no time is permission implied or granted to the downloader to adapt or modify AND SUBSEQUENTLY re-distribute their work in a different form and/or under a different name.
Permission to do that must be specifically requested on an individual basis, and received PRIOR to any further distribution of derived/modified works.
Having works displayed for download on a site such as Wincustomize.com does not legitimize or allow for the work to be downloaded by a third party and placed on other sites even under the original author's name. The author, and he alone, has authority to determine if and where his works are to be published/displayed.
If all that sounds too complicated, refer to jark's post...[it's short and sweet]...