Is it human nature to be hypocritical. Is it necessarily wrong that politicians are hypocrites?

People use the world "hypocrisy" as if it were the worst insult in the world, but everyone believes in something that they know is not true. It is wrong to dismiss a person by simply claiming they're hypocrites. If a smoker tells you to never smoke because it is bad for you; the smoker is a hypocrite, but he's also right...