For reasons that are not entirely clear to me, many political candidates are discovered to have exaggerated or (in some cases) flat out lied about their past achievements.
Currently, senate candidate Richard Blumenthal appears to have been caught claiming that he served in the armed forces in Vietnam, when he in fact served in a military unit that never went to Vietnam. The original national media report in the New York Times was deficient in that it did not tell the whole story, since the newspaper apparently decided to major on Blumenthal's alleged deceit over statements he made that he served "in Vietnam".
Blumenthal's attempt to claim service in Vietnam is part of a pattern of behaviour by many candidates for public office in the USA, who try to talk up any aspect of military involvement or service.
The irony in all of this is that, based on recent presidential election results, having any form of military service record is far from essential to winning elections. In 1972, Richard Nixon, who had not served in a war, beat George McGovern, a highly decorated WW II bomber pilot. In 1980, Ronald Reagan, who had no military service, beat Jimmy Carter, who had served in the military in WW II. In 1988 the story was more equal; George H.W. Bush, a WW II flying veteran, beat Michael Dukakis, who had served in Korea. Normal service was resumed in 1992 when Bill Clinton, who had avoided military service, beat Bush Sr. In 1996, Clinton beat Bob Dole, a WW II veteran with permanent disabling battle wounds.
Blumenthal's exaggeration of his military record is nothing new. Numerous candidates for public office have been discovered to have either exaggerated or invented aspects of their past.
My hypothesis is that this is common because the USA is moving towards becoming a low-accountability society. Electors and the media lack any consistent interest in fact-checking pronouncements by politicians and political candidates. As long as there is insufficient interest in checking on claims made by political actors at the time those claims are made, other candidates are likely to conclude that the risk of inflating their past achievements is worth the reward.
UPDATE - Another candidate has been apparently borrowing language from other politicians for his primary campaign. The irony here is that this is a Republican Party candidate apparently borrowing whole chunks of a speech by President Obama...a double whammy of hypocrisy and insulting the intelligence of smart electors.
UPDATE 2- Mark Kirk has been progressively caught in a web of duplicity and deceit over his military service...
UPDATE 3 - And now the best word on the whole sorry mess so far, from The Onion...
UPDATE 4 - And here is yet another example of a state-level elected representative who has apparently been claiming a professional football career that did not actually exist...