There has been some discussion about Joe's question and its relationship to the actual situation.
First, let me say the those defending Joe have a couple of points. It is not fair to say Joe was a "plant" by the Republicans without proof. Second, it is valid to critique Obama's response whether the situation was real or hypothetical.
However, I believe the negative reaction and the importance of the real situation should not be dismissed. The importance of Joe the Plumber as a symbol, one latched onto by the McCain campaign as evidenced by his repeated mentions in the debate, is at issue as well. To the McCain campaign, Joe the Plumber was a tangible symbol of the blue-collar working class American which they intended to use as a rebuttal to Obama's assertion that the average, middle class worker would benefit rather than pay increased taxes under his plan. I will admit, it struck me as strange when Joe was first mentioned, because although I know plumbers can make a very good living, it seemed at the very least unusual that one we bring home more than my family doctor.
The McCain campaign would not benefit greatly by showing a well-to-do financial advisor, bank manager, surgeon, or corporate lawyer who would be taxed higher under Obama's plan. They needed someone who represented the blue-collar type who would be hurt. They thought they had it in Joe, but that's where the reality of the situation becomes important. Since the situation Joe described seems to be considerable at odds with his actual situation, then using him as a symbol was a mistake at best, and misleading at worst. I don't fault the McCain campaign or accuse them of intentionally misleading in this case, but they should refrain from attempting to use him as a symbol from this point forward. If they want an example, they should actively find a blue-collar worker type who fits the situation they want to demonstrate. If they can't find one, perhaps they should find a different avenue of attack on the tax plan since it would seem at that point that Obama's claim to help middle-class workers is valid.