To someone constantly in the spotlight, there is a constant danger that one's private opinions sneak into the public domain.
Ferenc Gyurcsany's comments sparked riots in Budapest
The Hungarian prime minister's candid admission that his government had accomplished "nothing" and had been lying for "the last year and a half to two years" has infuriated the public, sparking riots in the capital Budapest.
Ferenc Gyurcsany's opponents are calling for his resignation, but the PM is not the first public figure to find himself in trouble after his unguarded comments were broadcast, or to have regretted an embarrassing gaffe.
The Republican Party leader in the United States Senate, Trent Lott, was forced to step down in 2002 after expressing the view that the US would have been better off if a candidate for president in 1948, running on a platform of racial segregation, had been elected.
Vice-President Dan Quayle was widely regarded to have scuppered his presidential hopes when a series of gaffes culminated in a clanger watched by millions on TV news broadcasts.
At a school spelling contest, Mr Quayle "corrected" a child's spelling of the word potato by adding an "e" to the end.
Jokes based on the mistake were to dog him for the rest of his public life.
Berlusconi's tongue has often got him into trouble
California Governor Arnold Schwarzenegger has got himself into trouble several times, most recently by speculating that a congresswoman's hot temper was down to her mixture of black and Latino blood.
He was forced to apologise for the comment, which was caught on tape.
Italy's ex-Prime Minister Silvio Berlusconi has made numerous comments considered beyond the pale by his critics - though many have been apparently misjudged public comments rather than private ones.
In perhaps his most infamous, he told a German member of the European Parliament, with whom he disagreed: "I know that in Italy there is a man producing a film on Nazi concentration camps - I shall put you forward for the role of Kapo [guard chosen from among the prisoners] - you would be perfect."
One of the most famous examples of a gaffe caught on tape was former US President Ronald Reagan's warm-up joke before a radio broadcast.
During the sound check he announced: "My fellow Americans, I'm pleased to tell you today that I've signed legislation that will outlaw Russia forever. We begin bombing in five minutes."
John Prescott let his personal feelings out of the bag
The tape was running and the announcement was leaked to the press, sparking an international furore.
Britain's former Prime Minister John Major was caught on tape describing un-named members of his cabinet as "bastards", in a comment that revealed how deep the splits in his Conservative Party ran.
The ministers were rebelling against his attempts to introduce the Maastricht treaty, which led to the creation of the European Union.
Mr Major was speaking casually after an interview with ITN, but was recorded by a BBC crew in the same room.
A more recent example involved the current US and British leaders.
Tony Blair and George W Bush were caught by a microphone during a break at the G8 conference in Russia.
Mr Bush greeted his ally with the words "Yo, Blair", and opined that they needed to get "Hezbollah to stop doing this shit".
Mr Blair's deputy, John Prescott, is renowned as a straight-talker, and has been accused at various times of making ill-advised comments or gestures.
The Duke of Edinburgh's gaffes are legendary in the UK
At one point he compared a crab in a jar to his party rival Peter Mandelson, joking: "You know what his name is? He's called Peter."
The Duke of Edinburgh, Queen Elizabeth's husband, is notorious for making jokes that might offend the recipient and make bystanders cringe - many of them based on old-fashioned racial stereotypes.
His comments have included: "It looks as if it was put in by an Indian," when being shown an old-fashioned fuse box; "Still throwing spears?" to an Australian Aborigine; and, to a Scottish driving instructor, "How do you keep the natives off the booze long enough to get them through the test?"
His son, Prince Charles, let some of his opinions of the press slip out at a press call in 2005.
Asked a question by the BBC's Nicholas Witchell, he whispered under his breath to his sons, who were standing next to him: "These bloody people. I can't bear that man. I mean, he's so awful, he really is."
It is not only politicians and royalty who have to watch their words, though.
The US Marine Corps last year had to publicly upbraid Lt Gen James Mattis after he cheerfully admitted on a panel discussion that he enjoyed war.
Caught on tape, he said: "Actually, it's quite a lot of fun to fight; you know, it's a hell of a hoot. I like brawling; it's fun to shoot some people."