When the air is thick with mosquitoes and humidity, it's hard to think kindly of this town. Civic boosters have tried for years, portraying Houston as a pro-business paradise while sidestepping the reality of living in a city built on a swamp.

The antidote to this approach came recently when a local marketing company began an independent, online campaign to promote Houston as it is, blinders off.

"The flying cockroaches. The flooding. The no mountains," says the ad, which goes on to list 17 more drawbacks before concluding that, in spite of it all, "Houston. It's Worth It." Residents are then asked to post their thoughts on why the city, unlovely and uncomfortable as it can be, is appealing all the same.

The point, said the ad's co-creator, David Thompson, is to acknowledge the worst and move on. "It sort of pulls the rug out from the easy place to go -- how can you stand the heat? -- and automatically takes you to a more meaningful conversation," he said.

Houstonians have responded so enthusiastically to the site, www.houstonitsworthit.com, that a technician reprogrammed the page to give people more room to write.

"I feel normal here. Maybe it is because I am imperfect like this city," one person wrote.

"The cleanest jail cells of any major metropolitan area," another said.

Then there was this analogy: "If Houston were a dog, she'd be a mutt with 3 legs, one bad eye, fleas the size of corn nuts and buckteeth. Despite all that, she'd be the best dog you'd ever know."

The campaign grew out of a conversation about a friend's magazine article on Houston's image, said Randy Twaddle, who helped conceive the ad. Twaddle is also Thompson's partner in a creative agency. "We had no intention of creating a slogan -- it just came out," Twaddle said.

The entrepreneurs decided to develop a Web site, then asked 100 friends and business associates to take a look. Word spread.

Although unsanctioned by an official visitors group, the concept has the support of influential Houston institutions such as museums, a children's advocacy group and Hermann Park, which houses the city zoo and an outdoor theater. The Web site got more than 50,000 hits in one day, but none from the tourism bureau.

Gerard J. "Jordy" Tollett, president of the Greater Houston Convention and Visitors Bureau -- which has spent $75 million in the past 30 years to promote the city -- declined to be interviewed. "He doesn't want to talk about it anymore," a spokeswoman said.

The last time Houston's slogan got much attention was in 1997, when Elyse Lanier -- wife of then-Mayor Bob Lanier -- led a $5 million effort to boost the city's image. Her group's catchphrase: "Houston. Expect the Unexpected."

Houston has experimented with a number of slogans that have mostly led to mockery. During the 1980s oil bust, the city was "Houston Proud." When the economy began to recover, billboards proclaimed that "Houston's Hot." The current city slogan -- "SpaceCity. A space of infinite possibilities" -- has not caught fire.

Thompson and Twaddle hope their tagline becomes so well known that it attracts visitors in the way Las Vegas's offbeat slogan -- "What happens here, stays here" -- helped lure 35.5 million tourists last year.