The site you have mentioned was still under consideration by the abuse team as far as I am aware when the second was created. As to it happening again if content outside the limitations of the ToS is placed on the site and Abuse are made aware - it is possible for it to occur. My suggestion to prevent this would to have your own 18+ notification somewhere on your site that also discourages users from posting illicit content to it.
Which site were you referring to Paradox?
Reality TV Forum has yet to violate any rules.