The online dating scene can be full of intrigue and mystery. Daters sometimes don’t know who they’re dealing with on the other end until it’s too late.

That’s why when Mindy Weiss is about to contact a prospective date through her favorite online matchmaking service, she now checks first to see if the person has a dossier on TrueDater (www.truedater.com). The new Web site allows people to review other users of dating sites and reveal whether they’re really who they claim to be.

"There are so many freaks out there," said Weiss, 27, of Los Angeles. "One check can make all the difference. This is like a friend telling me something about the person."

Online ratings and reviews are as old as the Web itself. EBay’s user feedback system – where sellers and buyers rate their experiences with each other – is perhaps the largest and most famous reputation-management system on the Internet.

Now a new crop of Web sites is sprouting up that aim to help Internet users view the reputations of their online peers. The sites attempt to hold people accountable for their online (and sometimes offline) behavior, both good and bad.

Stefan Brands, a digital identity expert in Montreal, points to the online dating scene, where a cottage industry has emerged to provide background checks of dating-site users.

"More and more organizations and people, when they’re dealing with people online, they need to know more about them," Brands said. "They want to know how they can tap into more information about them."

TrueDater founder Mark Geller said the idea for his site came to him while researching an idea for a TV show about an online dating company. Geller spent a lot of time using dating Web sites.

"People would lie a lot," Geller says about dating site users. "They lie about their pictures, about their age. They just misrepresent themselves. It just seemed to me there should be a site where people can post feedback."

TrueDater, based in Los Angeles, works by allowing people to evaluate the truthfulness of the online profiles that others have posted about themselves at dating sites, such as www.Match.com, Jdate and Yahoo Personals. Truthful profiles elicit a positive "TrueDater" rating.

A majority of the TrueDater reviews appear positive. But some take people to task for their alleged dishonesty in their profiles. "Picture is old ... he’s about 40 lbs. heavier in person than in the photo," read one review. "Completely dishonest about their entire self," said another.

Another new company, Opinity (www.opinity.com), of San Jose, Calif., allows people to collect all of their online identities and screen names – from message boards and gaming sites to eBay – into a single list so that others can more easily see the digital footprints they’ve left across the Internet.

Opinity users can register all or some of their various screen names with the service. Registered Opinity users can rate each other based on encounters they’ve had. Opinity uses those ratings to tally an overall "online reputation score" for each person. Opinity users can even begin to build a dossier – viewable by Opinity users – on people who are not registered with the service as long as they know one of their screen names.

Opinity founder Ted Cho said the service can help eliminate much of the anxiety and uncertainty of dealing with faceless strangers online.

"Whenever you’re interacting with people, if you had prior knowledge about the person’s past behavior, it could help you make an informed decision," Cho said. "Basically, what we’re trying to do is help people make informed decisions."

An example of where Opinity would be helpful, Cho said, involves a person trying to sell a camera at a certain camera-aficionado Web site. Although the seller has no reputation at this particular Web site, he could register his screen names from other camera sites on Opinity, and potential buyers could check his reputation there.

Cho said Opinity, still in testing mode, can have value even if two people never interact with each other. People can use it to judge, for instance, whether the person behind an online product review appears credible.

Owen Davis, co-founder and president of the company Identity Commons, said if Opinity creates a system where people are held accountable for their behavior and they can manage their own reputations, that could provide an incentive for honorable online behavior.

"The more invested I am in my identity, the less likely I am to waste it," he said. "The less likely I am to use it for evil."

As helpful as the reputation-management services can be, they also flirt with danger, experts say. Reviews are highly subjective, and individuals might find it hard to recover after someone has bad-mouthed them online.

What’s more, in the Opinity system, a person’s reputation could be harmed by something he said in a fit of pique on a message board years ago. Cho said Opinity users can get around this problem by choosing to exclude certain screen names from their Opinity profiles.

But David Evans, an online dating industry consultant and marketing expert, still has reservations.

"My problem with all these sites is that it’s very easy to complain about people, but none of them complete the loop and help people resolve their problems," he said. "If someone says something negative about someone, how do I repair that?"

NiftyGuy (www.niftyguy.com), a new San Francisco Web site where people can rate everyone from their favorite plumber to dentist, has posted some brutally honest reviews in its dating section. Often, the name of the person being targeted is used.

"Let his flattering lines draw you in, but let it end there," one person wrote about a male she had dated recently. "He’s a fun guy to hang out with, but very flaky and not the brightest crayon in the box."

Brand’s concerns extend beyond the effect on a person’s reputation. He worries that Web sites that collect and store online identity information present the same types of privacy risks as companies such as ChoicePoint, the Georgia company that keeps billions of records on Americans and which accidentally let private data get in the hands of thieves this year.

"If it’s properly done, maybe it will add some value," Brand said of Opinity. "But I don’t see how they will make it secure. It’s one more person who aggregates personal information. And that’s a bad business model for consumers."

But digital-identity authority Kaliya Hamlin urges patience.

"It’s a space that is evolving,’ said Hamlin, program director for a San Francisco non-profit. "I don’t think we know all the answers, but we need to experiment."

© 2005, San Jose Mercury News (San Jose, Calif.). Distributed by Knight Ridder/Tribune Information Services.