I can't remember the source right now, but I saw a poll once that has stuck with me for years.  It basically said our favorite presidents of all time seemed happy while doing their jobs. 

FDR always had a smile, even in the depths of the Depression.  JFK was incredibly witty, despite the tensions of the Cold War. 

Ronald Reagan knew how to give a speech that made us laugh -- or cry.  He even cracked a joke moments after he got shot.  You could tell he liked being up on stage. 

Bill Clinton loved the late-night policy debates, and we all knew it. 

Jimmy Carter, on the other hand, was pretty dour.  Richard Nixon seemed angry most of the time.  Jerry Ford, George H.W. Bush and Dwight Eisenhower took their jobs fairly seriously and didn't give us much to chuckle about.  They never seemed very joyous.  

Even George W. Bush, who many rate pretty low on "best presidents ever" scale because of some of the decisions he made, seemed to not take himself too, too seriously.  So he won a few brownie points for that now and then. 

I'll bet Obama would like to exude more happiness -- he used to do this, as I recall -- but those pesky Republicans keep getting in the way.  LBJ could spin a yarn but then Vietnam dragged him down -- and all of us with him.

So let's use this new measuring stick and think of how it might apply to last night's Democratic debate. 

Bernie Sanders has a message, to be sure, but it doesn't feel all that joyous.  He's mad as hell and he's not going to take it any more.

Jim Webb did not look happy in the Democratic debate last night.  He kept growling at Anderson Cooper that he wasn't getting enough airtime.  His talking points were all pretty stern, he even talked about killing someone.  It felt like his message was that the end of the world was near.  Maybe that's true, but even on the Titanic, the band played on till the end.

Hillary Clinton, on the other hand, seemed very happy last night.  She was especially happy when Bernie Sanders let her off the hook for the emails, and I think we all breathed a collective sigh at his attempt to put that issue behind us. 

I have always thought of Hillary as being almost "Richard Nixon-Mad" all the time, what with all her talk of conspiracies, etc.  She didn't show that last night and most agree she did very well.

Donald Trump clearly enjoys being the center of attention, so on some level, he's having fun with this.  But his message is often quite negative.  People are "losers," policies are "disasters," journalists are "mediocre," war heroes aren't really war heroes because they got captured. 

Trump has captured beautifully the anger that's out there, but it doesn't feel like his style would captivate for long.  It's all about trashing others, not so much about inspiring hope. 

If you put Ronald Reagan, John F. Kennedy and Donald Trump all in the same sentence, Trump clearly seems out of place.  Reagan and Kennedy inspired us.  I don't know about you, but I'm not feeling that from Trump.

As you watch debates from this day forward, ask yourself: Who looks like he or she is having the most fun up there?  Then compare those names to pundits' lists of "winners" in the post-debate discussion.  I'll bet you'll see a correlation.