During a rumination on the proposition that a slow-to-develop presidential campaign cycle could reduce opportunities for the thorough media vetting of candidates, Jonathan Bernstein makes this simple but important observation:

[W]hile I’m generally reluctant to be one who says that the internet changes everything, I do think this is at least plausibly a case where it matters. For one thing, in the old days — say, before the debut of the Hotline in the 1988 cycle — it was still possible for a local story to sit out there for a long time without anyone knowing it. No way could that happen now.

I’d agree, with the crucial qualification that in the past a “local story” about a presidential candidate did not have to be completely unknown nationally to be functionally invisible or at least unimportant. A great example was in 1976, when Jimmy Carter’s fairly elaborate and not-too-distant history of flirtation with segregationists was hardly a secret, but never became a factor during the Democratic primaries or the general election. Indeed, one aspect of that history, his vote for arch-segregationist Lester Maddox when the Georgia legislature was forced to elect a governor of Georgia in 1966, went almost entirely unnoticed.
Now it’s true that the staunch support of Andrew Young and the King family helped inoculate Carter from charges of past racism in 1976, along with Carter’s own decent civil rights record once he actually became governor in 1971. Indeed, Carter was very popular among African-American primary voters around the country (just like Bill Clinton years later, even though Clinton, like Carter, was perceived as less than ideally progressive, albeit never vulnerable to accusations of racism). But you have to wonder if Carter could have survived the kind of early exposure of and daily questioning about his past positioning on civil rights if he had been subjected to today’s levels of scrutiny and discussion.
My point is that modern media have not only made it harder to hide damaging information about politicians, but have made it harder to hide such information in plain sight, passed over as irrelevant or unimportant. To cite a seminal example, Trent Lott’s 2002 remarks expressing regret that Strom Thurmond hadn’t been elected president back in 1948 were widely reported, but it took relentless discussion of them by blogger Josh Marshall and others to make it something other than a “local story” of brief interest to Beltway insiders and Mississippians.
While it’s still possible for candidates and political parties–supported by friendly media–to “control the narrative” in a way that shoves negative information under the rug, it’s simply not as easy as it used to be. And that could very well be a factor in the decisions of potential 2012 presidential candidates to take a pass.