For what it's worth, I thought it was smart for Obama to go gracious on the Hillary-Bosnia scandal and suggest that they're both entitled to make a mistake every now and then. Obviously, the choice of questions isn't doing Obama any favors--bittergate, Wright, William Ayers!--but he's doing a decent (if low-energy) job not getting dragged into the fray,* and Hillary is coming very close to over-reaching by rubbing his nose in it.
*Like Isaac, I think the one exception was going on about the frustrations of working class people. He really needed to cut that answer off after his first pass through it.
--Noam Scheiber