"This was not the first time that Trump abused the truth this week. In a nod to fact-ignoring conservative fantasists, he raised the theory that Vince Foster, a Clinton confidant who committed suicide in 1993, was murdered. Trump did so despite the fact that multiple investigations, including by aggressive Clinton investigator Kenneth Starr, confirmed that Foster's death was a suicide. As conspiracy- mongering goes, this is worse even than Trump's association with the "birthers." He is using a dead man, whose family has pleaded to be left in peace, for a mendacious political attack. That is disgusting as well as dishonest."
Washington Post: 'Trump is pathologically dishonest and morally bankrupt'
Donald Trump isn't just a bigot. He's a liar. | Editorial
Four months after fundraiser, Trump says he gave $1 million to veterans group
"There’s a very good reason that this is the case: The American Right has become willfully disengaged from its fellow citizens thanks to a wonderful virtual-reality machine in which conservatives, both elite and grassroots, can believe anything they wish, no matter how at odds it is with reality."
Donald Trump, Mainstream Conservative
Trump the ripoff artist
"All of that is horrifying, but arguably scariest of all is his aggressive contempt for the truth. All politicians spin and twist facts to some extent, but Trump’s lies are so epic and recurring as to put him in a whole other universe of dissembling — a place where facts are meaningless and the truth can be anything he wants it to be at that particular moment."
Max Boot: Donald Trump’s lies are flatly disqualifying
"Having as President a man who treats rumor as gospel and refuses to acknowledge flat falsehoods would be disastrous for the country. A President has to sort through complicated, competing claims, figure out the best course of action and then make a convincing case to the Congress and the country. Trump’s track record suggests he is simply incapable of this kind of mental labor."