Who did they poll? If they polled a bunch of university students in boulder Colorado they might well have been correct in thinking themselves highly healthy. A lot of the most unhealthy groups in the US are also poor and somewhat outside te reach of casual academic sampling.
That said, although folks may not be as clueless as it seems, it's still a sad result.
The US data is from the NHIS 2009
http://www.cdc.gov/nchs/nhis/about_nhis.htm
...For 2006-2010, the households and noninstitutional group quarters selected for interview each week in the NHIS are a probability sample representative of the target population. Beginning in 2011, the minimum time length for a probability sample changed from a week to a month. With four sample panels and no sample cuts or augmentations, the expected NHIS sample size (completed interviews) is approximately 35,000 households containing about 87,500 persons. [...] The annual response
Of course, it turns out they're actually last among developed nations in real health outcomes.