There's often a disconnect in these cases between intensity of media attention and outrage among voters. So when the 24/7 cable news media zooms in on Weiner, everything appears much larger than in real life -- kind of like the photos he took of himself. In a classic historical example, Democratic presidential candidate Gary Hart dropped out of the 1988 race after the National Enquirer ran a photo of him balancing Donna Rice on his knee on a boat called Monkey Business behind his wife's back, yet polls suggested that a majority of Americans didn't support political disqualification based on adultery and felt the whole affair was overblown.
Often a scandal can be waited out. Viewers will grow tired, ratings will drop, news directors will instruct their staff to move on to other topics. Weiner has the option of simply stiffening up and soldiering on. Whether someone who hits on babes thousands of miles away from behind a computer screen will have the courage to brave it out is another matter.
Speaking of which, geography can also determine whether any given politician can survive a sex scandal. Weiner could trade his social media exploits for some much less sexy online language-learning adventures, then take his act to France or Italy. He'll suffer initial mockery for being a politico-sexual lightweight, but then it'll all be smooth sailing. Europeans have collectively considered the multiple infidelities of almost every elected representative from Jacques Chirac to Silvio Berlusconi and have asked themselves in each case if these men's cheating on their significant other means they're likely to screw over the electorate. The answer: Yeah, probably -- but not significantly more so than any European politician. The scum de la scum! Voters aren't electing husbands - thank goodness. Europeans just seem to be more realistic about what politicians represent and what to expect of them.
As we saw in the Clinton case, a battle-axe spouse who looks like she's ready to murder the transgressor with her eyes while he's sniveling out a mea culpa can also be useful in assuring sex-scandal survival. "OK, looks like she's got this covered," voters think. "Maybe we can move on to other things."
A final thing that endangers a politician's chances of surviving a sex scandal: photos.
While it may be easier to convey a thousand words with a quick snap of one's appendage, as Weiner did, it's nevertheless better to slow down and pound out those thousand words one by one. Not because letters would ultimately be any less damaging, but because they take a lot more time and effort for people to absorb and blow back out through their noses along with a mouthful of their morning coffee. Many won't bother. Letters also reduce the chance that Bill Clinton, your wife, or other important people in your personal or professional life will have an unexpected walk-on part in your pornographic montage, as was the case with Weiner when he captured framed portraits of them in his shots.