tommy your idea can defiantly work if you want to get around possible legal problems then have your paid submitters check a option to allow there galleries to also be listed at x tgp site for surfers to pay to get access to this way it covers you legally and will give that submitter the option to receive more traffic they will go for this anyway to be listed at another site to get even more traffic.
has for the actual site to do this on "I would do this" make a text listing of galleries with a traffic trade script to circle jerk the surfer but lets say 1 out of every 5 clicks the surfer is sent to a page explaining the option to pay x monthly fee so they dont get circle jerked and the paid version of the listing should have text and thumbnail version to keep your surfers paying that monthly fee. keep a extensive organized archive of multiple niches in text and thumbnail version of your "clean" listing and put in extra things to your site maybe giving away free dildos or free car oil whatever keeps them paying
surfers dont have to pay to see the latest galleries but they will have to pay if they dont want to be circle jerked and to be able to see the extensive archive and thumbnail version.
you might even just build your own galleries out of perchased content just for your 2$ surfers
and when it comes down legally "i dont think" there would be a problem since your are providing a service of organization to the surfer and traffic to the submitter and his sponsor.
if you told me your going to list my galleries behind a paid memberbased site id be very happy
conversion ratio would be alot better cuase those surfers got credit cards.