Actually, I think Hillary did mean what she said, but she could have phrased it better. A great many Trump supporters ARE racist, or sexist, or homophobic, or xenophobic, or Islamophobic, or any combination on this list. And a great many Trump supporters aren’t any of those things, but are desperate and feel that they are voiceless. They’re looking for some kind of change — any kind of change. That was the point Hillary was trying to make, but the point was completely lost by all the knees jerking on the right.
By the way, there is a methodology to scientific polls, and a margin of error. Most of the time, they’re right, and when they’re not right, they’re usually pretty close. One surveys a random sample of people, not just a specific group, such as rioters.