Five-point plans, engaging speeches and star endorsements are all important in a presidential campaign, but how well do candidates REALLY know the cities and towns where they're wooing voters?
The supreme test in Philadelphia: ordering a cheesesteak.
Just ask Secretary of State John Kerry, who was roundly mocked in 2003 for passing up the more traditional Cheez Whiz on his cheesesteak for Swiss cheese.
"Don't come into Philadelphia and try to cater favor with us and then order Swiss cheese, which no one does in Philadelphia," Ed Rendell, former Pennsylvania governor and Philadelphia mayor, said. Hillary Clinton, he predicted, will make no such gaffe should she sample a cheesesteak as she campaigns in the state before the primary Tuesday.
Bill Clinton "would always order a cheesesteak with onions and Cheez Whiz," Rendell said. "That is the only way to order a cheesesteak."
Competitive races in both parties have sustained the intensity of the primary face-offs far beyond their usual seasons this year, increasing the spotlight on candidates and the requisite local know-how. Most recently, in New York City, Ohio Gov. John Kasich took flack for eating pizza with a knife and fork, Hillary Clinton was mocked for struggling to use a Metrocard to ride the subway and Bernie Sanders revealed he thought the subway still took tokens, which were phased out in 2003.
Wading into the local sports arena can also go poorly. A month before the Iowa caucuses, Republican candidate Carly Fiorina was criticized for tweeting that she was supporting the University of Iowa in the Rose Bowl over her alma mater, Stanford. She later told CNN she was only having a "bit of fun."
Republican front-runner Donald Trump recently tried to rally a Pittsburgh crowd about Penn State University's legendary football coach. "How's Joe Paterno?" Trump asked the audience. "Are we gonna bring that back? Right? ... How about that whole deal?"
Paterno died in January 2012 just months after he was dismissed, a result of the child sex abuse scandal involving Jerry Sandusky, his former assistant coach. A campaign spokeswoman later said Trump wasn't talking about Paterno himself but about his statue, which was removed from outside the football stadium four years ago, angering students and many alumni.
Sometimes a simple fashion choice can set tongues wagging, like when former GOP candidate Marco Rubio wore a pair of stylish ankle boots in Iowa over the winter, triggering some teasing.
Whether or not these moments are disqualifying, they can reinforce an unwelcome perception about a candidate. Mo Elleithee, who served as Clinton's spokesman in the 2008 race, said the problem is when things go badly and "it feeds into a narrative that already exists." So it was for Kerry and his cheese choice in 2003; it fed into the perception that he did not relate to common people.
Political history is full of such faux pas. In 2007, Republican Mitt Romney drew derision from the crowd at the Iowa State fair when he flipped a pork chop off a grill, picked it up and put it back on. In 1992, George H.W. Bush was ridiculed when he seemed wowed by electronic price scanners, suggesting he had barely ever set foot in a grocery store.
Still, Elleithee, now the executive director of Georgetown University's Institute of Politics and Public Service, said there is also an upside to getting the candidates out there.
"You do those types of events, you do those types of photo ops if you want to show the candidates in everyday settings," Elleithee said. "There's a natural barrier between presidential candidates and the public. They become caricatures. Campaign staff is constantly looking for ways to help them see the other side."
Admittedly, this is not always easy. In Philadelphia, as if ordering the cheesesteak is not enough, Rendell said he also offers advice on how to eat what can be a messy sandwich.
"You have to do what's called a Philadelphia lean," Rendell said. "You have to lean over to make sure the juice goes on the pavement."