Should journalists give up lying sources?

From Glenn Greenwald:

They're not protecting "sources." The people who fed them the bentonite story aren't "sources." They're fabricators and liars who purposely used ABC News to disseminate to the American public an extremely consequential and damaging falsehood.

More from Greenwald on this here.

My answer to this question is a resounding "Yes." The contract between a journalist and an anonymous source is something like this: Journalist gives source anonymity. Anonymous source gives journalist hard-to-get information. If the information is false, then the contract should be shattered. If the anonymous source isn't exposed, then there is no incentive for anonymous sources to tell the truth.

Jay Rosen explains it well:

But the only way that system can work is when sources know: if you lie, or mislead the reporter into a false report… you will be exposed. People who believe strongly in the need for confidential sources should be strongly in favor of their exposure in clear cases of abuse, because that is the only way a practice like this has a prayer of retaining its legitimacy.