In A Sane World questions the presumption of truthfulness that DJT enjoys by virtue of...actually it is not entirely clear why DJT was presumed to be telling the truth, subject to onerous and cautious "fact checking" while his Democratic opponent was made subject to endless wild accusations that needed to be put under the microscope, with the zealous enthusiasm of Fox News and the for-profit fabricated stories online.
In Philadelphia, DJT overuled his teleprompter in a garbled statement "Here in Philadelphia, the murder rate has been steady - I mean - just terribly increasing". Of course, statistics show that the murder rate has been steady. Trump thus demonstrates his affinity for lying - he starts with a lie, because it works to his advantage. And when presented with the facts - even by his loyal staff - he quickly pushes the lie instead. He prefers lying.