For my part, it strikes me that Obama’s ratings are a bit oddly high given the bleak conditions in the country. It’s clear that a very large number of people are still basically blaming Bush for the situation.OK, on to my wild and irresponsible speculation: I strongly suspect that not only is Yglesias correct (that Obama's current 49%, per Gallup today, is a bit higher than it should be), but that the biggest contributing factor is the Republican's rejectionist strategy and embrace of the crazy. Alas, I have no idea whether that's true or not. But I sort of think that it is. As far as the mechanism, it's about crying wolf: since the most visible opponents of the president have shown that they're going to take a maximal position against whatever he does, weak partisans and independents heavily discount everything they say.
Part of the reason that it's irresponsible is because I'm aware that there is work on presidential approval ratings, and I'm not willing to spend the time right now looking into it. I do know, however, that they aren't purely determined by economic performance (or by scandal). Those things matter, but there's more to it than that. I don't think I've ever seen any research indicating that opposition strategies can matter, but then again I'm not sure that there's a lot of evidence one way or another.