To the best of my knowledge, I don't think Donald Trump has paid for a single ad on television.  He has created a lot of ads, but he has just put them on the internet, and they've gone viral.  Or he's simply tweeted comments, or done stunts like his latest effort, where he sent bottles of Trump-branded bottled water to Marco Rubio:

Donald Trump is escalating his attacks on Sen. Marco Rubio with a special delivery for his rival: "Trump Ice Natural Spring Water."

Trump has previously trained his fire on Rubio, claiming he has the worst voting attendance record in the U.S. Senate and that he sweats a lot. But CNN learned that the Trump campaign sent a "care package" to Rubio's Washington campaign office that contained a 24-bottle case of "Trump Ice Natural Spring Water," with Trump's face on it, two "Make America Great Again" towels and bumper stickers and a note reading, "Since you're always sweating, we thought you could use some water. Enjoy!"

A Trump campaign aide said they added the towels "for him sweating," and described the overall gesture as a lighthearted prank.

Rubio gained attention for his 2013 Republican State of the Union response when he desperately grabbed for a water bottle and conspicuously gulped it on air. He poked fun at himself during the most recent GOP presidential debate. But it was after that debate that Trump started commenting that Rubio was sweaty.

"I've never seen a young guy sweat that much. He's drinking water, water, water. I never saw anything like this with him with the water," Trump said while speaking in South Carolina last week.

Politicians have never seen or done anything like this.  Their attack ads have all been about positions on the issues, or attacks about scandals.

Trump's attacks have been what might be considered "personal," which typically would be seen as out of bounds.  But I think he's on to something.  For a lot of voters, their decision on whom to support is about character.  That's why so many people like Trump.  They have no idea where he stands on most issues (myself included), but they like his perceived "tell it like it is" character.

Similarly, Bernie Sanders inspires leftist audiences because, unlike Hillary, he is perceived as being intensely sincere in his desire to move toward a kinder, gentler dictatorship of the proletariat – once the bourgeoisie have been neutralized, of course.

So I think attacks on character are not just legitimate, but effective.  Jeb Bush fell in the polls not because he attacked Trump; he fell because Trump responded and labeled him "low-energy" and without passion.

Marco Rubio is young, and from his mannerisms he is perceived to be nervous and unsure of himself – not a quality you want in a president of the United States.  By accentuating that aspect of Marco that is already there, Trump is effectively calling into doubt Marco's fitness to be president.

Trump is like those caricature sketch artists you sometimes see in the park.  They paint a portrait of someone, grossly exaggerating facial features, but still working with features that actually are there.  It makes no sense to draw someone with a big chin if he doesn't have one already.  And it's funny to send Marco Rubio bottled water and a fluffy towel only if he already seems sweaty and nervous.

Unfortunately, the other candidates are unlikely to take up this manner of attack.  If Ben Carson is nominated, he'll be gentle as a lamb against Hillary Clinton.  Ted Cruz will be argumentative and immensely logical but soft-spoken.  And the other candidates will be even worse.

Exit question: Trump has been sliding in the polls lately.  Do you think his rapier wit will enable him to politically shish-kabob Marco Rubio and Carly Fiorina (the latter in a way most respectful to women, of course!)?

This article was written by Ed Straker, senior writer of NewsMachete.com, the conservative news site.