I do not believe the President’s sex life is any of our business. After thirty years of political reporting, I have been unable to establish a link between marital fidelity and high performance in public office. It really doesn’t matter who they screw in private, as long as they don’t screw the public.

Molly Ivins (1944–2007) American writer, political columnist [Mary Tyler Ivins]

Essay (1998-03), “A Dodge Too Far,” The Progressive, Vol. 62, No. 3
    (Source)

In an interview (2006-10-09), "Who's It Screw, and Who's Doing the Screwing?" by Rosalind Alexander, Seattle Weekly, Ivins used a similar line:

I have been watching politicians for 30 years, and I have never found a correlation between marital fidelity and high performance in public office. So I just decided a long time ago, I don’t care who they screw in private, as long as they’re not screwing the public.