If anyone reasonably intelligent says that they think Donald trump is smart, you need to dare them to watch an unscripted trump speech in its entirety.
After an hour of that they’ll either change their minds or go insane.
His manner of speaking doesn't negatively impact his politics. In fact, it has rocketed him to the top and kept him there. So can it really be called stupid? Rule #1 of public speaking is to write for your audience.
His direct audience of utter fucking morons does see him as smart, because they are so dumb.
There is also an indirect audience that sees him as smart/competent because they only see his carefully picked quotes and clips that edit out the idiot-ramble that he’s had his entire life.
He's not saying anything meaningful or funny. He's just saying stupid shit his mostly White male audience already agrees with so they can whoop & clap.
"You know another problem with wind? Thomas Dolby. He sings about the wind. Next thing you know, he's polluting our airwaves with ringtones and blinding us with science. OPEN YOUR EYES, AMERICA!"