Maybe it was the exhaust fumes I choked on when the lodge's "eco-tour" motorboat driver gunned the engine, buzzing a grizzly that had wandered too close to shore. Or maybe it was the lodge manager's bemused look when I asked if the mahogany floors were made from sustainable lumber or the endangered rain forest kind. But at some point on my visit to this fishing camp turned luxe wilderness lodge, I became viscerally aware that I'd been mistaken. It was a low blow to the ego for an experienced eco-traveler -- and it left me feeling outraged.

Many dirty practices hide beneath a green veneer: an "ecotourist hotel" in Chihuahua, Mexico, dumping its garbage into scenic canyons; safari operations in Kenya's Masai Mara National Reserve clear-cutting riverbanks for firewood; and an "eco-lodge" near Tortuguero National Park, Costa Rica, using outdoor lights that disrupt the nesting habits of endangered turtles.

"Eco" and "sustainable" are trendy in the corporate world and the lodge biz these days: Ecotourism is growing three times faster than conventional tourism. But at a time when environmentalism is as much a marketing tool as an earnest philosophy, being a true eco-lodge isn't nearly as easy as saying you're one.

"The word eco has been hijacked," says Hitesh Mehta, an eco-lodge expert with EDSA, a landscape architecture firm in Fort Lauderdale, Florida. Like organic food, yoga, and feng shui before it, ecotourism has entered the realm of the lucrative fad, where exploitation is inevitable. Rising gas prices have made people think more about dwindling resources, and last year's hurricanes drew more attention to global warming. "There's a lot more awareness about the effect our lifestyles are having on our environment," Mehta says. "People are becoming more conscious about it."

In some ways, though, the ecotourism movement got started accidentally. "There are a lot of people who are interested in this idea of being close to nature but with a little more comfort than traditional camping," says Stanley Selengut, whose Maho Bay resort in the U.S. Virgin Islands helped pioneer the eco-lodge concept in the late 1960s. He developed the property ecologically because a local park ranger convinced him that doing otherwise would cause erosion that could ruin the area's snorkeling. He didn't realize there was a market for it until years later, when a travel article drew about 3,000 inquiries. With rates starting at $75, Maho Bay is affordable as well as comfortable, but many of today's lodges are high-end operations. Swatting at tsetse flies in a cramped hut or tent is no longer the norm. Rooms often cost several hundred dollars per night -- serious cash to drop on a vacation if you're not sure it's being well spent.

Unlike shopping for organic groceries, where the packages are clearly labeled and products are regulated by the government, shopping for an eco-lodge requires more legwork. (See "How to Find a Great Eco-Lodge, left.") Don't hold out for some kind of certification: Martha Honey, executive director of the International Ecotourism Society, says a globally recognized certification is still years away. In the meantime, all we have are guidelines.

A true eco-lodge has three basic elements, Mehta says: It protects the environment, benefits local communities, and helps guests learn about the local surroundings while they explore them.

Beyond that, eco can exist at lots of levels. Like a shopper choosing between the "100% Organic" snack and the one "Made With Organic Ingredients," an eco-tourist has to decide on an acceptable shade of green. Are you comfortable paying top dollar even if it means being potty-trained by a composting-toilet instructor? Will you be angry if you have to forfeit lobster because it's on the local endangered species list? Will you cross a place off your list if they wash towels only once a week?

Defining eco may be tricky, but it's easier to know what eco isn't. Don't be fooled by so-called "eco-resorts" that have cropped up all over the developing world since Costa Rica demonstrated that ecotourism can be profitable. I once asked the owner of an "eco-hotel" on Lake Titicaca in Peru what made the hotel ecological. His answer: "We don't allow smoking." A 601-room eco-resort in Brazil keeps exotic animals from the nearby rain forest in cages; in El Salvador, I was taken on an "eco-tour" to a park where shrubs were sculpted to look like various animals and a helicopter.

Not far from the B.C. fishing camp gone awry, I found a lodge that epitomizes North American eco-luxe. Nimmo Bay is a planet-friendly playground for adventurous greens who can afford to splurge -- everything from steelhead fishing to river rafting is done by helicopter, and nightly room rates start around $2,000 per person. It gets the bulk of its power from a waterfall, works with First Nations tribes to preserve the area's cultural integrity, and goes to great lengths to treat its sewage: Its $80,000 Hydroxyl waste-management system uses ozone to render human waste immaculate before pumping it into the bay (this I learned during a behind-the-scenes exploration that owner Craig Murray calls "the poo tour").

It's not surprising that a lodge known for paying attention to every detail would do so at the microbial level, but not all of Murray's neighbors share his passion for environmental protection. Some fishing lodges, cruise ships, and entire coastal cities dump their raw sewage into the water -- legally. Murray has become something of a crusader for B.C. water issues, from pollution to wild salmon preservation. He does it, in part, because his guests demand it. "People want to feel as if they're not contributing to the degradation of the environment when they go to enjoy themselves," he says. "We make our own certification program: the guests. They return if they're happy."