Well, I guess I would respond this way. As far as Hillary goes, it's not surprising she performs relatively well right now. She's very well known. She was first lady, a Senator from New York, a high profile candidate for the Democrat nomination in 2008, and just completed a term as Secretary of State. Having said that, Clinton's job at State was, essentially, non-political and that has definitely boosted the image most have of her.
A well-known analogy. I remember seeing a projection of an Obama-McCain contest that showed Obama winning 27 electoral votes -- those of Illinois, Hawaii, and DC. But know well -- Barack Obama was still little known.
Also know well -- most projections show Hillary Clinton basically winning states that Barack Obama won, so she is far behind John McCain at this stage.
George W. Bush would be widely seen as a disaster as a President by the early autumn of 2008 -- but through the middle of 2006 he wasn't. Not until the November election was it clear that Dubya was a disaster on foreign policy, his "mission accomplished" proving increasingly less than accomplished. The economy was still chugging along... but wise people saw how sordid its realities were. Those people did not shape the election.
Dubya was still getting away with a bungled war and an economy based on a rip-off (a speculative boom financed on predatory loans). In 2006 the wars in Afghanistan and Iraq were beginning to go bad, and by November the Democrats offered a solution. Many of the inexpensive ads looked like this:
https://www.youtube.com/watch?v=qbAaJf34OJo No. Dubya created those problems with his reckless foreign policy and the worst economic stewardship of any President in decades. Dubya would have created fewer problems had he promoted the usual Republican policy of promoting thrift and industrial investment with low taxes and limited spending. Instead Dubya was a reckless spender in ways that Republicans usually attribute to Democrats, and his reckless spending exploded on America. So did the speculative boom.
Had I been a conservative Republican I would have promoted thrift and industrial investment with the expectation that people getting jobs would be able to qualify for cars, houses, etc. But that's not the sort of policy that the GOP stood for around 2001.
Barack Obama hasn't started any budget-busting wars. He has not supported a speculative boom likely to go bust. He is very cautious. He does not create problems as Dubya did.
What is more 'toxic' is that we are no longer so tolerant of Presidential misconduct, reckless spending, and rash foreign policy. We are too fussy to tolerate another George Worthless Bush, and in the toxic environment that Dubya created for trust in politicians, our fussiness could be a good thing.
President Obama seems to be taking the rap for Democratic 'failure'... and it is still possible that Obamacare will work well for Democrats.