At the end of June, the House of Representatives voted to extend the $8,000 homebuyers' tax credit, by an extraordinary margin of 409-5. The Senate approved the measure on a voice vote. At a polarized political moment, this near unanimity was noteworthy in itself. Conservative Republicans and liberal Democrats, from cities and suburbs and small towns across the country, joined together to shower a bit more taxpayer largesse on one of America's favorite industries: real estate. But there's a problem with this bipartisan idyll.