May as well blame Bush, he doesn't believe in fighting back on worthless attacks.
When Dean launched his 50-State strategy after 2004, I was one who warned that this was going to pay off in the long run and GOP ignored the implications at its peril. 2006 was a taste of things to come, because Dean knew what he was doing and had the courage to take the heat while looking at the long-term.
The Worth of attacks will be measured by the results at the polls, and so far, Bush has failed miserably to defend against attacks which have paid off handsomely for the 'rats.