Will the Foley scandal costs the Republicans votes, as is often suggested? In my view, not so much. When foreign policy, terrorism, and social issues are the questions of the day, the Republicans tend to do well. It doesn’t matter so much if the Republicans have botched those very issues, provided those issues make the headlines. Those are the issues which make the Republicans seen important. Voters punish Republicans for bad governing "in the polls" but not always "in the booth."
The North Korean crisis helps the Republicans. Even the botched war in Iraq helps the Republicans. No matter how badly the Republicans do, people (rightly or wrongly) trust the Democrats with national security even less. Along related lines, the Republicans will never get much credit for the rather high levels of discretionary spending pushed by the Bush Administration. Even bringing up such spending gets voters in a "Democrat frame of mind."
The Democrats have their best chance when voters are focused on the economy. It is neuroeconomics at work; the very topic activates the part of the brain that leads people to vote on way or the other.
It was safe to vote for Clinton once the Cold War ended. More generally, Republican competence in foreign affairs is the greatest friend the Democrats have right now.
Think about it.