So Joe the Plumber doesn't have a plumbing licence, doesn't own the business he works for, and wouldn't pay more under Barack Obama's tax plans if he did.
Given that the McCain campaign barely vetted his Vice-Presidential pick Sarah Palin, they were never likely to check out the blue-collar icon of the final Presidential debate pitch. Let's hope the media frenzy doesn't warn off any other normal voters thinking of engaging with the political process.
It reopens the debate about the public politics of taxation. Can progressive parties put tax and spending plans to the electorate and win?
The Obama plan - that nobody earning more than $250,000 will pay more in taxes - has gone down well with undecided voters in the Presidential debates. (There are clear majorities, across voters for all parties, for higher taxes above similar levles in the UK).
But the Joe the Plumber story demonstrates the risks of voters much further down the income scale believing they will shortly earn much more and get hit, or that politicians who pledge taxes at the top - and also of being misrepresented by political opponents or the media, as when Labour was mugged over its shadow budget in 1992 by the 'tax bombshell' campaign. That experienced seared, for a generation, the message: Don't talk about tax.
Dig a little deeper, and the key issue is about trust in whether and how the money will be spent. That was Labour's problem in 1992.
Despite New Labour's pledges not to raise income tax rates (and the basic rate has been lowered), Mark Gill of MORI has shown how voters in 1997 and 2001 expected spending and taxation to rise. That can be a vote winner, but there must be confidence that the money can be well used.
It seems unlikely that the story of Joe the Plumber - whatever the truth - could cost Obama the election, when voters are sceptical about whether John McCain and the Republicans have the response they need to the economic downturn.