On the merits, I think the possibility that IRS employees intentionally targeted conservative political groups is a huge deal while the fact that there was some bureaucratic CYA in the initial Benghazi talking points is a nothing-burger. (If and when new information emerges on either issue, I'll update those opinions, of course.) But which scandals catch fire and which don't isn't entirely a question of merit. It's also a question of circumstance.

President Obama speaks about the IRS and Benghazi at a news conference. (Washington Post)

Political scientist Brendan Nyhan has researched the conditions in which scandals are most likely to take hold of the public imagination. And the current moment, it turns out, is particularly fertile soil for scandals to take hold, for at least three reasons:

1) "New scandals are likely to emerge when the president is unpopular among opposition party identifiers. Obama's approval ratings are quite low among Republicans (10-18% in recent Gallup surveys), which creates pressure on GOP leaders to pursue scandal allegations as well as audience demand for scandal coverage."

2) "Media scandals were less likely to emerge as pressure from other news stories increased. Now that the Boston Marathon bombings have faded from the headlines, there are few major stories in the news, especially with gun control and immigration legislation stalled in Congress. The press is therefore likely to devote more resources and airtime/print to covering the IRS and Benghazi stories than they would in a more cluttered news environment."

3) "Obama is in his second term, which is when scandals are most likely to take place."

"For the White House," Nyhan concludes, "things are likely to get worse before they get better."