Here's a pollster who joins my coolness on the Democratic Party's blame Bush strategy, but nonetheless finds polling support for the idea. It is in feeling of voters who say they are undecided on whether to vote Republican or Democratic in the fall.
At the same time 51% of them think the current state of the economy is still George W. Bush's responsibility to only 27% who think it's Obama's, and 55% of them would rather have Obama as President to only 28% who are feeling Bush nostalgia.
These folks aren't happy with how things are going. But they were even unhappier with how things were going a couple years ago. Playing the Bush card may just convince them it's better to stay the current course, even if they don't love it, than to go back to the old one.