I think that it doesn't matter if you getting information from scum- if a theif/murderer wants to work for you by giving you information and it's reliable information, who cares.
Question is begins when they doing things for the CIA, like steal things, break things, and murder people. The main difference I guess is are they freelancing or working for CIA. For instance we have bounty reward for Bin Ladin. It doesn't matter who does the deed [or what they had to do to do it], what matters is proof he is dead or the live body to transfer. But don't think we should hire scum to go get Bin Ladin. You hire people who are capable of following orders. It's simple: I wouldn't want to hire a criminal, I don't want him in my house, I don't want to trust him with my dog. If he is an ex-criminal that's slightly different. And of course if he is a criminal according to someone like Saddam, he may not actually be a criminal/low life.

If the CIA absolutely *must* hire criminals/low life then they should set up some kind of proxy group and liason with this group {whorehouses can be successful privately operated {and an ex-prostitutes probably would run it best}, but I don't think whorehouses should run by the goverment]. A proxy group would have it's own set of problems- similar to using a proxy army, but think in total this has easier problems to deal with and if done right they can be mitigated.