My mind goes back to Bob Hawke, who was famous for crying in public. At the most convenient times, too.
The first time I remember was when he was "forced by his conscience" to defy his party discipline in order to vote for sending peacekeepers to the Sinai (to supervise the Camp David treaty). This was, of course, before he became Prime Minister. His support for Israel, in opposition to the general anti-zionism in the Labor Party, was mostly genuine, I think; but this display didn't exactly hurt him with the press, or with Jewish donors.
The second time was when, just when he needed a boost in the polls, he revealed that his daughter was a drug addict, and he cried about it, and his vote among female voters went through the roof.
The third time was when he confessed to having cheated on Hazel, and cried genuine tears of bitter remorse, on TV. By that time we were used to the sight, though, and I'm not sure how many people bought it.