I say 90% of them are cracked. There is a pretty simple way to find out if the software is nulled.... But overall, Nulled IPB sucks because not only does it potentially expose you to being a sleazy jackass for stealing someone's copyrighted software. But you can NEVER trust someone nulling such software, Especially one that could provide access to a'lot of things. Say it had a Facebook login, well what if that login is the same one to your Online Banking? Or Paypal? It's just not worth it.
Moral of my story is: An Open Source a day keeps the lawyers away. (or go pay the $175+ for the legit copy).