Second-term grumpiness liberation
I've always thought one factor in the infamous second-term lame-duck slump in poll numbers is that many people support any given President because they don't like the other guy, or the other guy's party. Once the necessity of getting their candidate re-elected is gone, people feel more free to let their hair down and grouse, at least until the concluding months of the term arrive, and it's Legacy Time.
Like you, I find it amazing that anyone could sincerely find much to approve of in Obama's performance of late, beyond the general sense of blood-sport gratitude that the hated Other Guys lost the election. Then again, how much attention are the Low Information Voters paying to what's going on at the moment? The dearth of positive news doesn't automatically produce a negative sense of abandonment or betrayal. They can't find much to celebrate, but for the die-hard supporter of any President, that doesn't automatically translate into disapproval.
I suspect the media bias you mentioned plays into that. The media is not going to invest any effort reminding voters of Obama's campaign promises, highlighting the ObamaCare train wreck, pointing out that his foreign policy is a mess, or even dwelling on the endless grinding unemployment that Obama voters have accepted as the New Normal.
And when it comes to Scandalpalooza, well, the press is barely mentioning most of it. Only the IRS and NSA stories have found much traction. (Notice how swiftly Media forgave President Boyfriend for spying on them.) There was just a poll that said strong Obama supporters think the Tea Party is a greater terror threat than radical Islam. They're not going to get too bent out of shape over the IRS acting as a bludgeon to suppress Tea Party votes.
To be honest, I suspect the only reason Obama's numbers have "cratered" is that he's been lying low while the scandals blow past, and even some of his firm supporters find it a bit puzzling that the all-powerful Unitary Executive claims he learned about them by reading his morning newspaper. His big War on Energy speech left a lot of his voters cold (what happened to your umpteenth Pivot to Job Creation, boss?) and some of them hopping mad. It will be interesting to see if Obama can do something to get his old mojo back, or remember how much they hate the Other Guys in time for the big 2014 midterms.