Oh, I know for sure that they can and will enforce the auction site restriction 'cos eBay.co.uk pulled my Poser Pack listing then sent me this e-mail

"We would like to let you know that we removed your listing:

7127214705 Poser Pro Pack for Poser 4 for Windows GENUINE boxed wi

because the intellectual property rights owner notified us, by a signed statement, that your listing or the item itself infringes their copyright, trademark, or other intellectual property rights owned by them.

We have credited any associated fees to your account. We have also notified the bidders that the listing(s) was removed, and that they are not obligated to complete the transaction.

If you relist this or any other similar items on eBay, your account is likely to be suspended.

If you believe your listing was ended in error, or have questions regarding the removal of this listing, please contact the intellectual property rights owner directly at:

Curious Labs, Inc.
copyright@nukepirates.com

eBay is available to answer questions, but since it is the rights owner that requested the removal of your listing(s), we encourage you to contact them first.

For more information on eBay's cooperation with rights owners through the VeRO Programme, and a list of rights owners that have created About Me pages, please visit:
http://pages.ebay.co.uk/help/policies/questions/vero-ended-item.html
http://pages.ebay.com/help/community/vero-aboutme.html

Thank you for your cooperation.
Regards,
Customer Support (Trust and Safety Department) eBay Inc"

Cheers,
Mark