It seems to be written in stone: Politicians lie. How they lie, and what they lie about, seems to be often (though not always) less important than the fact of the lie itself. Lies, in politics, are low-hanging fruit for the opposition's focused attacks.
The recent kerfuffle over Texas gubernatorial candidate Wendy Davis' biographical inconsistencies has been the topic of Facebook debates, Twitter feeds, and has been food for much media feasting. Some parts of Davis' biography are beyond dispute: She was at one point a single parent, there were times she struggled financially, she went to Harvard, and at some point married and divorced lawyer Jeff Davis, who paid the freight during her last two years at Texas Christian University, and supported her through Harvard Law School. The underlying story behind Wendy Davis' rise to success is a powerful story of hard work and perseverance. That being said, it seems as though Davis wouldn't need to take liberties with the truth to prove the point she was trying to make. Whether she simply misspoke or had a memory lapse, those types of missteps call integrity into question; and giving conservatives further reason to attack her on the basis of her historical honesty (considering that they're already showing their true sexist, misogynistic stripes by attacking her with straight-up woman-hating jabs), weakens her, and forces her to divest valuable time defending against what, in the end, are largely irrelevant details. While Davis now admits that she needs to be "more focused on the detail," the damage in some ways is done. Being forced to defend even minor rhetorical missteps places a candidate in the unfortunate position of losing the high ground.
Rand Paul faced criticism and scrutiny over his plagiarism. Mark Sanford's pack of lies about his whereabouts (more than the fact of his Argentinian mistress) while serving as Governor of South Carolina temporarily derailed his political career. Michele Bachmann's record of lies (75% of her statements were rated "false" by fact-checkers) caused her to barely squeak out re-election - and to ultimately resign rather than face another one. There are myriad other examples of political lies - small lies and whoppers - which caused political candidacies to stumble. Who actually knows how many elections have been lost because candidates fudged the facts on the most basic, fact-checkable elements of their lives?
Americans are a tough audience. We often don't like the truth when we hear it, but we also don't like liars. But in the final analysis, "the truth will set you free" is more than just a cliche; in fact, in politics, the truth is a formidable foe.