True, but when you have hundreds of millions of dollars directed at one person over several years, approval can slide from 66% to less than 40%, even with the best defenses.
Take me, for example. I was a big supporter of Clinton in 2012. I even donated to her campaign. But, several times during the 2016 campaign I actually caught myself thinking that I didn't trust her. And, I had to remind myself why I liked her.
So, whatever they did, it was very, very effective. It really sapped a lot of supporters motivation, at the very least.
George Lakoff has written some interesting books on the topic of reframing. I recommend reading some of his work. I'm sure that the science has evolved considerably since 2004, when I first read him.
https://www.amazon.com/George-Lakoff/e/B000APCCII