(Fortune Magazine) -- In the summer of 2005, I found myself in Wyoming, preparing for a 10-day hiking trip in the wilderness with my dad and a group of serious outdoorsmen. The men had the usual gear - tents, fishing rods, freeze-dried food, bug repellent-and some unusual gear: not terribly masculine cloglike shoes made of a perforated rubbery substance.

Now, I consider myself a shoe connoisseur - they spill out of my closets, colonize my floors - but I'd never seen anything like these, or, frankly, anything quite so hideous.

Crocs: If you'd been told years ago you'd be wearing these, would you have believed it?

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Some People Think Bulldogs Are Cute There's a long tradition of ugly shoes becoming popular. Some offenders: Uggs Surfers started wearing these Australian boots, then fashionistas began sporting them with miniskirts. Would that the surfers had chosen miniskirts instead. Birkenstocks A California woman discovered these in Germany in the 1960s. Wearing them with socks is not technically a crime, just an abomination. Jellies A leather shortage in France after WWII led to the these PVC sandals. They were a craze in the '80s, as were leggings. Leggings are coming back. (Oh no!) Earth Shoes The Scandinavian shoe has a negative heel-the heel is thinner than the sole. That's horrifying to those who wouldn't leave the house in flats.

"Why would you wear such a thing?" I asked.

The men explained that the shoes, called Crocs, were perfect for fording a stream or wearing around camp. They were lightweight - only six ounces each - easy to slip on, extremely comfortable, and inexpensive (roughly $30).

The shoes were so perfect that one of the men had even bought a pair in baby blue, because that was the only color left in the store.

Today, the question is no longer why anyone would wear Crocs, but rather, is there anywhere they shouldn't be worn?

Celebrities like Al Pacino and Teri Hatcher wear Crocs, as do their children. Red-haired chef Mario Batali wears his orange ones on TV; movie star Adam Sandler wore his khaki ones on the red carpet.

I've seen lime-green Crocs on hipsters on Manhattan's Upper West Side, yellow ones and orange ones on teenagers in the Chicago airport, and tiny pink ones on tiny girls and little blue ones on little boys in the suburbs.

Michael Atmore, editorial director of the footwear group at Fairchild Publications, spotted Crocs at a book signing in fabulously wealthy East Hampton in early August. "They were all everyone was talking about," he says.

In 2003 the company that makes Crocs-Crocs Inc., (Charts) which is now publicly traded - sold 76,000 pairs of shoes worth some $1.2 million. This year, analysts expect it to sell close to 20 million pairs worth almost $300 million.

The Croc is the latest triumph of two counterintuitive (to some of us) concepts in footwear: comfort and ugliness. The shoe, which is made by injecting a special foam resin into a mold, was invented by a Canadian company called Foam Creations.

In 2002 three Boulder buddies in search of a business idea, Scott Seamans, George Boedecker, and Lyndon "Duke" Hanson, took a boat trip to the Caribbean. Seamans had brought along a pair, and all were struck by their unique properties.

"The first thing I said was, 'Man, are those ugly,'" recalls Hanson. But then he put them on. "It's like walking on Nerf Balls," he says.

Unlike other clogs, this shoe was cool and lightweight, and both slip- and smell-resistant. (The resin is "closed cell," which means that bacteria can't take root.) The partners promptly struck a U.S. licensing agreement with Foam Creations.

Since "Foam Creations" lacks a certain something, the partners thought about a new name. Hanson says he was keen on crocodiles because they're good on both land and water, live a long time, and have no natural predators.

Then he realized that when the shoe is viewed from the side, it slopes up like a crocodile's snout.

Sold. "Croc" it was.

The newly christened Croc was a hit at the 2002 Fort Lauderdale boat show, and it took off from there, largely due to the many accolades for its comfort. (As one blogger - there are many blogs about Crocs - put it, "You have to put on a pair and try them and, I swear, you won't care if they look like donkey balls, you'll just love them.")

Crocs Inc. acquired Foam Creations in June 2004, and in February 2006, it went public. The company now sports a market value of more than $1 billion and is rolling out more styles. "We've created our own category of footwear," says Hanson.

As I obsessed about the sudden proliferation of Crocs, I realized that they are not so much a new category as the latest in a pantheon of ugly shoes that became a fashion phenomenon despite - or maybe because of - their bad looks.

Think Jellies, Earth shoes, Birkenstocks, and most recently Uggs, to name a few. (Remember the Ugg-boot with miniskirt look that swept through New York and L.A. and then everywhere else a few years back? No? Lucky you.)

"There's a long tradition of the underground alternative ugly shoe thing that is a backlash to $600 Manolo Blahniks," says David Wolfe, creative director for the Doneger Group, which analyzes fashion trends.

That tradition is a conundrum to those of us who think of shoes as exquisitely crafted, expensive torture devices. At a recent conference in Toronto, I was teetering along in a pair of beautiful three-inch Christian Louboutins, a heavy computer bag over my shoulder, and I have to admit I was eyeing the Crocs in front of me longingly.

But comfort be damned.

I'm with Manolo, of Manolo's shoe blog (which has no official relationship to Manolo Blahnik), who has consigned both the Ugg and the Croc to his Gallery of Horrors, which he calls a "permanent exhibition of the worst of the shoes."

Other pundits, though, say that ugly can have a cool all its own.

"Boomers love bulldogs," explains Marshal Cohen, chief industry analyst for the NPD Group, a provider of retail data. (Wait a minute. I happen to love bulldogs. There are different standards for dogs and shoes.)

He adds that wearing a deliberately ugly, yet extremely comfortable, shoe can be asserting one's superiority to the dictates of fashion. "It's a way of saying, 'I'm successful. I don't have to care,'" he says.

Ted Allen, one of the stars of Queer Eye, says, "Part of being stylish is being contrary." (Allen, whose boyfriend owns two pairs of Crocs-iridescent green and basic black-says that the shoes are fine on the streets of Chelsea, but only with neutrals, and he would not recommend them for a job interview at Bear Stearns.)

The problem for Crocs Inc. and its investors is that fashion phenomena often don't make lasting businesses.

Will the Croc be a Birkenstock - or a Jelly? And now that Crocs are everywhere, where can they go? "My sister in central Indiana is wearing them," says Allen. "I wonder how much longer this can last."

Indeed, as I do some deep sole-searching, I can't help wondering if my inability to embrace Crocs is due to their ugliness, or because everyone else is ahead of me.(Check out the new Georgie boot, though. It's pretty cute.)

Some people question whether Crocs can successfully expand into other styles, which may explain why a whopping 33% of Crocs stock is sold short.

"If you made the Hula-Hoop, you can't diversify," says Wolfe. (Actually, there's hope: the maker of the Hula-Hoop, Wham-O, also introduced the Frisbee, the SuperBall, and Silly String.)

Even the founders of the Croc grudgingly admit that the shoe has its limits.

Asked if he'd prefer a woman in an evening gown to wear Manolos or Crocs, Hanson says, "If I'm brutally honest, I'd put her in the Blahniks." Then he pauses. "But have you seen the pictures of Faith Hill in Crocs? Man, does she look good."

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