Actually, I don't personally care, except I have at least some admiration for his bold and honest approach to "politics as usual", and I feel that his frowning, pouty look definitely detracts from any positivity that his overall political platform attempts to reflect (IMhO).
Mr. Trump can smile, and his smile might be one of his most powerful assets; I think he should capitalize on it, because I really think that 'pout' doesn't help him.
I think there's actually more to The Donald's pouty frown than just a matter of 'biting his tongue' or otherwise 'champing at the bit' (yes, it was originally "champing", now it's frequently "chomping").
I really think he is maybe trying a bit too hard to 'think on his feet' when it comes to some of the facts and figures he attempts to rattle off.
He does quite well, but I think he sometimes lets his mind run too far ahead of his mouth (or vice-versa?) and his pouty (almost 'arrogant' looking) expressions seem to reveal some of the 'wheel-turning' that's going on in his head.
Anyway, this is mostly just "for what it's worth"...because I believe that EVERYONE should try to smile more, and, most especially, if they're trying to convince people to vote for them, right?