Mark, the real problem, IMHO, is lack of healthy skepticism.
The polls continue to show that the voters think that Bush is of good moral character personally, despite their discontent with his performance in office. Perhaps they understand that he runs an administration where mendacity is treated as a family value, and just don't associate deception by politicians with bad moral character, or perhaps they misunderestimate the extent to which Bush and his aides make up for their profligacy with public funds by observing a strict economy with respect to the truth. Probably, both are the case.
I don't believe your average voter is as jaded as you suggest, but I agree, they may "misunderestimate" Bush. However, I think the real sickness of the American voter is gullibility. I'm weary of excuses from people along the lines of "Bush must know something we don't—he can't give out all of the intelligence now, it would aid the Enemy." People simply don't know how to be skeptical of their leaders.