Trump seems to have some antiquated ideas on certain minority groups and nationalities but he doesn't seem racist like those tiki torch fucks.
He used to work/meet and mingle with people of color well before he was President and was pretty progressive on who he hired for his projects.
'real' racists would be opposed to that idea. In fact it fits Trump pretty well that he was friends with Michael Jackson and the likes as he sees himself sort of as an excentric misfit.
He also supported O.J. Simpson, Bill Cosby and Tiger Woods long after it was cool.
On the flip side there's the birther thing and the page ad he took out to ask for the death penalty for suspects who were later acquitted.
However in Trump's case, when it comes to Americans like Warren, Obama, Clinton or Acosta... the grudges seem more on a personal level than singling or calling out groups of people.
Which is precisely why it is hard to make 'racist' stick.
Nixon is also weird in this regard. He could be racist with his comments and in tapes but his policies told a different story. He understood that better race relations would benefit the country more than a racial divide.
In fact, I think that pretty much sums up Nixon. He felt morally superior and smarter than his opponents. He had to do those things because he knew better how to run the country than anyone else.
And he could set aside his own 'feelings' to do what in his view was right for the country. He had a pretty bad case of god-complex.