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.