Doonesbury by Garry Trudeau for June 25, 2008
Transcript:
Alex: You can't imagine how much garbage there is out there about Obama, Dad... one evil rumor after another. I was up all night trying to prove negatives. Mike: Prove negatives? Alex: Yup. Mike: I thought that was philosophically impossible. Alex: It is. That's why they give it to volunteers.
Only in limited contexts. In the sense the saying is usually meant it’s accurate.