The third presidential debate  was arguably the most substantive of the general election, but that wasn’t a high bar to clear. It was also probably Trump’s best performance against Clinton, but it still wasn’t nearly good enough to close the gap between them. His refusal  to say simply that he would accept the result of the election became the main takeaway from the debate and the banner headline in practically every newspaper. Trump was very likely to lose the election anyway at this point, but he seems determined to lose it in a way that will bring even more discredit on him and his supporters. He managed to overshadow everything else he said during the debate with that one answer, and anything else he said–for good or ill–will receive very little attention. Since Trump was already trailing Clinton going into the debate, the onus was on him to score a clear victory. He did not, and he missed his last major chance to make the election more competitive. That failure is his, and no one else did it to him.
Clinton was forced to dodge questions about donors to the Clinton Foundation and her support for a “no-fly zone” in Syria, but that was the result of tough questioning from the moderator. Her answers to these questions were woefully inadequate and evasive, but her opponent didn’t take advantage of them. Trump never really managed to get the better of Clinton the entire night, and he tended to ramble aimlessly in response to questions that might have worked to his advantage. On more than one occasion, he ended up railing against the nuclear deal with Iran in response to questions that had nothing to do with it. This not only kept him from giving a coherent answer to the questions he was asked, but it also showed how heavily he relied on discredited hawkish talking points when he ran into difficulty. At one point, Trump tried to attack Clinton over New START, which he laughably called “the start-up.” Even if there had been merit to Trump’s criticism, he made such a hash of it as to make his attack useless.
The result of all this was that Clinton was able to escape scrutiny of most of her record. She was never asked to defend her support for the Libyan war, nor did she really have to answer for anything else that she did as Secretary of State. Once again, her opponent didn’t know enough to know how to use her record against her. Despite her poor record on foreign policy, Clinton was able to get off almost completely scot-free.