When both Bill and Hillary Clinton cried, their poll ratings went up, but, in Britain, blubbing isn't such a sure-fire hit.
Tony Blair cried when he found out Dr David Kelly had died and was out of office within a couple of years, while his successor, Gordon Brown, wept when talking about the death of his daughter and was humiliated in the 2010 election.
So the signs aren't that great for Ken Livingstone, who this week cried not in the face of death, but instead went all moist over a campaign video, not a genre usually known for its dramatic weight.
On the other hand, the Mayoral election is more like a talent show audition than normal politics. Maybe Ken's tears could help position him as the caring choice in contrast to Boris Johnson, whose recent "you're a f***ing liar" explosion feeds into the idea of the Tory candidate as a Bullingdon Club oaf - a bit like the way the more sensitive panel on the The Voice have beaten bully Simon Cowell's Britain's Got Talent team in the Saturday night ratings battle.