I would say they keep them secret because other "black projects" are being conducted there, otherwise they would be just torture camps.
Also I am very sure its not just the CIA that run these black sites and torture people.
As a side note if the torturing of one person leads to information that could save thousands or more.....whats wrong with that? the only bad thing I
see in these camps is when it is done just for fun or on people that hold no information that is of such vital importance that it can be gained no
other way.

