BEWARE, ladies.
Manny from Miami is not quite the sensitive single man he says he is. He is married with a kid, no less, and "he sleeps with women everywhere," according to his anonymous former girlfriend in a posting on DontDateHimGirl.com.
As for Vincent of Jacksonville, his ex said she answered a knock at her door one day only to find his wife and his mistress had come calling. The two, having found out about each other, "don't mind teaming up to get rid of the next girl," the ex-girlfriend said in her posting. "Whatever you do, don't date him, don't speak, just move on."
And Michael, the 23-year-old from England? "He only cares about himself and how many notches there are on his bedpost," reported one of the women he counted as a notch. "Ultimately, he'll end up sad and lonely. Probably with a hefty bout of gonorrhea."
Unearthing a potential mate's cheating, thieving, maybe even psychotic ways during the early stages of courtship has always been tricky business. But it is particularly difficult today, when millions are searching for dates online and finding it far easier to lie to a computer than to someone's face.
But the Internet is now offering up an antidote. Web sites like DontDateHimGirl.com, ManHaters.com and TrueDater.com are dedicated to outing bad apples or just identifying people who may not be rotten but whose dating profiles are rife with fiction.
Framed in pink, the DontDateHimGirl.com site allows a woman to post the name and photograph of a man she says has wronged her, along with a short but often pungent synopsis of how precisely she was aggrieved. The suspicious or merely curious can hunt for a cheater by typing a name into the search engine. Women can also send e-mail messages through the site if they want to ask more pointed questions about a particular cad. In a slight nod to fairness, men who disagree with the characterization can write a rebuttal to be posted alongside their names.
"It's like a dating credit report" for women, explained the Web site's founder, Tasha C. Joseph, a public relations specialist in Miami. She said that 170,000 women have registered to use the site and that they have entered information on 3,000 men.
While many women find the Web sites amusing and sometimes helpful, they have enraged men, guilty or not, some of whom send e-mail messages or call the posted phone numbers to have their names and photographs taken down. They argue that the Web sites are biased and damaging, particularly if the story being told is false. And while the women remain anonymous, the men are offered up in full detail.
ManHaters.com, also known as WomanSavers.com, which features a drawing of a woman dressed in red, carrying a pitchfork and sprouting tiny horns, has a questionnaire that generates a rating of a man as good or bad from zero to 122; most men end up in the muddled middle. The multiple-choice questionnaire allows women to check off descriptive statements ranging from "stinks, has body odor, bad breath and doesn't care" to "He has the perfect balance of humility and confidence."
TrueDater.com is among the sites geared to online daters of both sexes and the untruths they tell behind the Internet's wall of virtual anonymity. The site can warn a woman that the purported 6-foot-4 Wall Street stockbroker with bulging pectorals is really a baldish, 5-foot-10 Wall Street Journal deliveryman with man breasts. Or it can alert men that a supposedly unmarried woman with the dimensions of a lingerie model is actually a married woman who hopes to achieve those dimensions with a little help and a lot of money.
Users post the nickname that the person in question uses on an online dating service like Match.com, and warn that the posted profile is misleading. A click of the mouse can send the curious to the person's profile page. Not all the news is negative. People who tell the truth are flagged approvingly as "true daters."
The warnings on TrueDater.com, which are edited, must relate to the posted photograph and profile. So if someone turns out to be a cheapskate, but never claimed to be a big spender on the profile, the site's editors strip out remarks about stinginess. Not so if the dater is married and claimed to be single.
"With the advent of the Internet people can be what they want instead of what they are," said Ms. Joseph, 33, who started DontDateHimGirl.com last year after she and her girlfriends swapped one too many stories about devious men. "You think this guy sounds great. Turns out he's married and he's got five kids."
She said her site, which she likens to the F.B.I.'s most wanted list, receives 250,000 hits a day. "Using the Internet to out these cheating guys gives these women a bit of a weapon," she added. The sites seem to be thriving because false advertising is epidemic in online dating profiles. Joe Tracy, the publisher of Online Dater Magazine, estimated that 30 percent of daters using online services are married, a number he said has steadily risen.
But Mr. Tracy cautioned that truth-in-dating Web sites may also be guilty of publicizing falsehoods, and the resulting harm to a man's reputation can be complicated to undo. Writing a rebuttal is effective only if the man knows that his face and name are listed on the Web site. He may not.
"The least that these sites could do is contact the man who is being posted about for a rebuttal," Mr. Tracy said. "It's only fair he knows it's up there." As for the anonymity granted a woman, Mr. Tracy said, "If this was a court case, he would know who the plaintiff is."
One man was so furious with Don'tDateHimGirl.com that he created a Web site in October to solicit men for a lawsuit. So far none has been filed, Ms. Joseph said, adding that she does not know exactly who is threatening to sue her. But www.classaction-dontdatehimgirl.com, the man's Web site, makes plain his objections:
"If the target was your father, your mother, your sister, your brother, your friend, your co-worker, your husband, your wife, your lover and the words were being spread not in a legal trial but in a public display of hatred how would you feel?" the site asks. "If someone's life was damaged by slander what could be done about it?"
Attempts to contact the Web site's founder were unsuccessful.
Ms. Joseph, who is planning to start a companion Web site for men, DontDateHerMan.com, said she understands the anger her site provokes. But she added that women must be granted at least a semblance of anonymity to protect them from harm. As for lawsuits, Ms. Joseph and the creators of similar Web sites note that people who post their stories have to check a box saying that they are being truthful.
"It's a bulletin board for women, and the women take full responsibility of everything that they post," Marlon Hill, Ms. Joseph's lawyer, said. "They attest to the veracity of their stories and photos."
Andrea Wells of New York City heard about DontDateHimGirl.com from a friend a few months ago and signed up. She knew just the guy to expose, a handsome, charming would-be rapper named Serge. The two met at a concert a year ago and dated for five months, she said. She went to his house just once and thought the place looked overly spare. There were few clothes in the closet, for example.
Their relationship ended abruptly when Serge's disconsolate wife sent Ms. Wells a message from Serge's BlackBerry, alerting her that Serge was married. Thinking back to her visit to his house, Ms. Wells realizes "he hid everything — wedding pictures, shampoo."
"I posted his story," she said. "It's public knowledge. Everyone should know. A marriage license is public knowledge."
And while she acknowledges that every story has two sides, "It's a perfectly good thing for women to check," Ms. Wells said. "At least it gives you a heads up."
Roberta Lipman of New York, an artist and real estate agent, does dating due diligence on TrueDater.com. Reading profiles on sites like Match.com is like reading code, she said. Take the word "separated" as a description of marital status. See it and run, she said.
"Online dating is tricky," said Ms. Lipman, who said she is in her 40's. "There is so much room for hidden agendas."
Back when old-fashioned blind dates were in vogue, the person was at least vouched for by a friend or relative, Ms. Lipman said. And while personal ads in publications were also risky, a person couldn't go on and on about his or her attributes in a space the size of a Post-it note. But online conversations can easily get out of hand and go on for months. People can invest time and emotion in a person who turns out to be a romantic fiction.
"You can tend to fall in heavy-like," said Jamie Diamond, director of community relations for TrueDater.com. "It's not just, 'I missed out on a half hour of going to Starbucks.' "