Michael Barone has an excellent column in today's issue of The American examining how the voting public perceives that status of the economy. In past decades, both Republicans and Democrats tended to agree on whether the economy was good or bad. In recent years, however, that's changed. Even during periods of robust economic growth (e.g., 2002-2006), Democrats tended to rate the economy much worse than Republicans.
Then, after the election of George W. Bush, the divergence between the two parties expanded into a chasm. It began to widen during the recession of March-November 2001, and it widened much more as the economy recovered and resumed low-inflation growth. By early 2006, a time of vibrant economic growth, 56 percent of Republicans said the economy was excellent or good, while only 28 percent of independents and 23 percent of Democrats agreed.
There is a divergence here between Democrats' and independents' assessments of their personal economic condition, which have generally been positive, and their assessments of the economy as a whole. It's hard to resist the conclusion that when Democrats–and, in 2004-2006, independents–were responding to questions about the condition of the economy, they were actually responding, "I am a Democrat," or, more emphatically, "I hate George W. Bush.
In the end, Barone says, economic policy is much more likely to reflect the partisan interests of the candidate rather than an objective assessment of economic conditions.