The New York crowd understands full well what Trump was doing. He was not actually calling Iowans stupid in the literal sense as in saying you are stupid people. The phrase “Are you stupid?” Or attaching stupid as an adjective is for better or worse a figure of speech in this region to denote something unbelievable. In this instance, Trump in effect says that he can’t believe Carson is this high in the polls based on an unbelievable (to him) story. So he makes a statement and follows it by a reference to being stupid. We do this all the time here. As an example, say someone will make a statement that the Jets will win the Super Bowl, a normal discussion might be “The Jets haven’t won since Namath, they’ll never win, what are you stupid?” So this is a case of Trump being Trump. Question is, will the larger population understand this and be okay with it.
That is how I remember New Yorkers speaking.
But, it’s a common expression when talking about something unbelievable.
My dad would say, “Jack’s beans grew as high as a magic kingdom with a goose laying golden eggs. Are you stupid enough to believe something like that?”
And I wasn’t.
I think that “stupid” might become one of the banned words from the left. Fortunately people understand that Donald is the unPC candidate and don’t want to make a “dumb” decision on his candidacy.