Signs Your Beau Is Bad News

We're all familiar with bad boys -- the guys you hate to love but find irresistible.

There are hip and hot Hollywood bad boys of the moment -- like actor Colin Farrell and Britney Spears' husband Kevin Federline -- and then there are the quintessential cool, bad-boy characters everyone fondly remembers, like Fonzie on "Happy Days" and the sly but sexy thief portrayed by Brad Pitt in "Thelma and Louise."

But there's a big difference between a celebrity bad boy, a fictional bad-boy character, and a dangerous man in real life.

For some women, that difference can be hard to spot. Bad boys appear charming to mostly everyone, but are really different people living a web of lies.

Scott Peterson, who was described as a perfect, handsome gentleman by friends, is sitting on death row for killing his pregnant wife, Laci, and unborn son. Robert Chambers, the so-called "Preppy Murderer," served almost 15 years in prison for strangling Jennifer Levin in New York City's Central Park after meeting her in an Upper East Side bar.

So how can you tell the good guys from the bad?

Psychiatrist Keith Ablow offered these tips on specific things to look for to see whether you were dating a man who might harm you -- physically or psychologically.

Some women may see these signs and gloss over them because they want to believe in the romance of the situation, but these tips from Ablow could save your life.

Signs You're Dating a Dangerous Man

He has no friends. People accumulate friendships and relationships if they are relatively normal. You might like to think that you're the first person in somebody's life they can connect with, but you have to think, why would that be? It's because everybody else is running the other way, that's why.

He dismisses all of your opinions. This means you don't matter to him, which means that it's a hop, skip and a jump to you don't exist.

He drinks to excess or takes drugs. People who drink a lot or take drugs are trying to dampen their emotions, which could be hostile emotions. Also, a lot of violent crimes are committed when someone is under the influence of drugs or alcohol.

He's broken the law. You might like to think that you are reforming someone or that a mistake was made and he didn't really do it. But make no mistake, breaking the law is a bad sign.

He seems too good to be true. Then he probably is! People have rough edges. But, people who are trying to deceive you have no rough edges, they've polished them all.

Lines to Watch Out For

When a man says these lines, here's what he really means according to Ablow.

"Only call my cell phone. Never call my home phone." He's either married or involved with someone else.

"I've never had a true friend until I met you." What he means is that people usually run the other way when they get to know him.

"I called you eight times during lunch because I was worried about you." This line might feel good to some people because they want to feel that they matter. But what someone is really trying to tell you is "I own you. Your lunch hour is mine."

Ablow has a syndicated talk show that will debut this fall. Check the show's Web site to find out where it airs in your market.

ABC News' Robin Roberts reported this story for "Good Morning America."