not sure if this is true, but I heard several times that you also find "stolen" objects there. Commercial objects, just slighlty modified and then placed there for free.
There´s also no info about the people running the site and the buy ads links is handled by a different company as far as I can tell - so even there you don´t get info about the people behind the site.
Perhaps I am to paranoid, I might be totally wrong - but ususally, when something looks to good to be true, then it simply isn´t true ;-) So perhaps keep that in mind when surfing around over there.