Case and point- what they do is clip about 5 pixels around the edge automatically this will 90% of the time remove the copyright info
http://www.babedump.com/viewimage.php?pid=4080 copyright info almost complete as it is printed large. The link is one of BabeDump's direct sponsors.
Another example:
http://www.babedump.com/viewimage.php?pid=3795 obviously not public domain, yet no copyright mark.
This One Was From my test gallery:
http://www.babedump.com/viewimage.php?pid=4250
the logo is cropped, the copyright image at the bottom is gone, and the link submitted was
http://studentdeals.us the link when posted was changed to
http://www.wastetimeonline.com which is one of their top referrers.
If my sponsors knew that their copyright info was gone, and that no link to my site which would take users to their site eventually, they'd be pissed.