1. Liars

In a recent survey, it was found that most online profiles contain some sort of lie, whether it's the person's age or -- in some cases -- relationship status. White lies -- adding an inch to height or dropping a couple pounds -- are the most common and not a big deal to most people.

Consider these facts according to the April 2007 issue of Proceedings of Computer/Human Interaction:

·    About 52.6 percent of men lie about their height, as do 39 percent of women.

·    Slightly more women lie about their weight (64.1 percent) than men (60.5 percent).

·    When it comes to age, 24.3 percent men lie compared with 13.1 percent of women.

When it comes to misrepresenations of age or relationship status, be careful or you could get seriously burned. In one recent case, a woman met a man on a popular dating site with whom she immediately hit it off. She even put her life on hold to go with him to Dubai when he was transferred for work. Eleven months into the relationship, she came across an e-mail -- from his son! What's more, the e-mail said something about "Mom" saying hi. In one fell swoop, our poor girl found out the man she met online was not only a father -- he was married! She moved back to the United States and has given up on online dating since.

How to Avoid Them:

Ask questions. Though it may be listed on someone's profile, someone's age is fair game in the questions department, so feel free to ask your potential date how old (or young!) they are. You may find that 35 suddenly becomes 42. While you don't want to ask too many questions and scare the person away, it's perfectly fair to verify the big things: age, weight, height, and -- most of all -- whether or not that person is, in fact, single. Half the time, people lie on their profiles to get people interested -- nine times out of ten, someone will level with you about their stats once you show some real interest, since they know they might have a chance of meeting you in person.

2. Photo Fakes

Dating site traffic analyses show that profiles with pictures are clicked on twice as much as those without. Having a good picture of yourself can be the difference between getting seen and getting lost. However, some people take the notion of "looking good" a little too far. They post misleading pictures that can trap you into thinking you're meeting your dreamboat only to find a shipwreck waiting for you. Let's face it, not everyone looks as good as George Clooney or Angelina Jolie.

Joan, a woman from New Jersey, had thought she met Mr. Right. He was charming and -- according to the picture on his profile -- quite handsome. She looked forward to seeing his auburn hair and deep eyes when it turned out that Mr. Right had gone gray. He also hadn't seen a gym in years. Turns out that his profile picture was over five years old. While there's nothing wrong with gray hair or a couple extra pounds, people who misrepresent their looks aren't being honest.

How to avoid them:

Look for profiles with more than one picture. People who choose only flattering angles could be hiding something. Ask for a recent picture, and if the person refuses, you could be looking at that person's high school yearbook photo. And if someone looks as good as George Clooney or Angelina Jolie, you need to double-check that it's for real.

3. Fixer-Uppers

Most marriages end in divorce -- that's just a fact of life. But many people on the rebound make their profiles all about what they don't want. The truth is, these people are on the rebound and are likely to still be living with the wounds of their last relationship. You may be in for some serious scrutiny, criticism, and baggage-handling, so beware. Imagine, for example, what any of Sir Paul McCartney's new lovers must think as he talks about his past relationships!

Consider these recent profile headlines:

• Cheaters Need Not Apply

• Tired of Meeting Women in Bars

• No Manipulative B*thces, please!

• Please Don't Be A Liar

• Felons, potheads and jerks need not apply

What we have here are jilted lovers. Run. Run away. While it's a good idea to learn from your past relationships, no one wants to date a bitter, angry person. By telling people what you don't want, you're scaring off potential mates.

On the other side, if you're reading profiles, avoid these singles as they are either recently out of relationships or still getting over something pretty big. They're not ready, and you don't want to be their fixer-upper.

How to avoid them:

To steer clear of the fixer-upper at all costs, watch out for the aforementioned profile headlines. While you may hate the same things these rebounders do, you still shouldn't pursue a relationship with them. Having something in common can be great, but those things should be positive, not negative. As the old saying goes,"You must love yourself before you love another...."

4. Membership Fishers

You finally got a response to your profile, and she's hot! You're all set to respond to the beauty queen, but there's one problem: Her profile happens to be over at some other site.

Of course, before you can send her a note on her profile, you're asked by the new dating site she's listed with the to sign up. Before you know it, you're a member of a new dating site, and it has your credit card info, and, it turns out, your new love doesn't exist.

Dating sites make their money on membership dues, and with thousands of them competing for daters, they're in a vicious fight to get you to sign up. Some wily sites have taken to trolling single people from other sites, making them think that a new lovely wants to meet them... at a new site that requires signing up.

How to avoid them:

Make sure anyone you hear from is already signed up with the online dating site you're signed up with. If someone responds to your profile, it means they already have a profile at the site you are using. Don't fall for the "meet me over here" tactic. If they really like you, they'll come talk to you where you are.

5. Cheaters

How is it possible that this new, wonderful person is still single? In fact, he or she may not be. While there are some great singles out there waiting to steal your heart away, some of them are not, in fact, single. Surprise, surprise, it turns out that some people use dating sites as a way to get a little something on the side when they're out of town.

Consider this story about Jill, a 27-year-old Washington, DC, marketing executive, who met the "man of her dreams" online: