Of course if you ask people how they were doing 3 years into Bush they probably remember things were going well.
And of course since the crash at the end of his administration was based on things that were not directly caused by his administration you would have a hard time bashing him on the economy at all.
What the left needs to do is keep mentioning Bush. The history re-write that the pop culture did now declares him a bad president.
That way Obama can run against Bush again, and not have to mention his actual failures!