When Hillary Clinton allegedly shut down one floor of a luxury store so she could get a $600 haircut, her grooming choices highlighted the media blowout that always surrounds candidate hairstyles.

Haircuts have been a theme in every major presidential campaign cycle over the last decade. In 2007, John Edwards was criticized for saying he paid $400 for a cut. During the last presidential race, Rick Perry's hair got several of its own Twitter accounts, but still couldn't hold a candle to Mitt Romney's perfect coiffure, which earned its own share of memes.

This time around, Donald Trump's hair, just like the person beneath it, is dominating the conversation. There are almost as many memes inspired by Trump's hair as there are memes inspired by his gaffes.

The attention isn't entirely misplaced. An oft-derided but entertaining study comparing how Presidents part their hair and how it matches their ratings points to a connection between hair and leadership. The results show that only six presidents have parted their hair on the right, and every one of them, except for Reagan, ranked poorly. The majority of presidents have had a left part. Bald presidents or those with no part or a center part were the highest rated.

The paper suggests that men who part their hair on the left are commonly viewed as popular, successful, strong and traditional, while men who part on the right are seen as unusual and eccentric. (Hitler is probably history's most famous right-parter). Left-parters don't necessarily have a better chance at becoming president—but it just so happens that most white men are left-parters, and most presidents have been white men. The study asserts that women with right parts are seen as gentle and caring, while women with left parts (like Clinton) are seen as intelligent, reliable and masculine.

With constant exposure during modern election cycles, it's no surprise that candidates would want to spend top-dollar for wardrobe and hair—especially Clinton, whose hair comes under constant scrutiny from political and lifestyle publications alike. If any of the other candidates' hair was being featured in the likes of Town and Country, Harper's Bazaar and InStyle, they might be spending hundreds of dollars on their hair too (if they aren't already).

So which candidates have the most "presidential" hair? We asked celebrity hair stylist Rodney Cutler for his professional opinion.