Trump is spouting racist rhetoric popular a century ago, like "racehorse theory" — see Trump Praises Good Genes for Haaretz's comparisons to the Nazi era.
Trolling Techniques: (1) Outrage —> (2) Anger —> (3) Circle the Wagons cycle
Dog whistle politics has changed. In the past, a "dog whistle" was when a politician said something that his supporters would know was racist, but centrists wouldn't hear it. Only supporters, only the target demographic that the speaker intended to mobilize, heard the dog whistle.
I watched good folks start to tear into each other when this window decal made its way to a political facebook group.
I'm guessing: this image is seen as wildly racist to some, and a silly joke about lousy ex-boyfriends to others.
And there is a big danger: when people don't think they're sharing something racist, and then get accused of it, they tend to feel pushed out, not called in. This is creating, over and over, a feeling of rejection among a large part of the country.
This provocation is done very much on purpose: