We’d all like to think that we have some sort of sixth sense that will warn us when we’re truly in danger, some animal instinct that raises the hair on the backs of our necks, gives us goose bumps and sends us running in the opposite direction.

Retired FBI profiler Mary Ellen O’Toole, Ph.D., is here to tell us the truth about trusting our intuition in perilous situations. In “Dangerous Instincts: How Gut Feelings Betray Us,” she outlines how to protect yourself and your loved ones from bad people. Her tips are especially useful if you’re thinking of doing some online dating, hiring a contractor/nanny/assistant, or letting your child’s coach or another parent give him a ride home.

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It’s perilous out there, and you could just crawl under the covers (with your entire family) and never come out. Or you can learn from O’Toole’s 28 years of experience as an FBI agent, 15 of them as a profiler with the Behavioral Analysis Unit (BAU)—the work popularized by shows like CBS’s “Criminal Minds.” O’Toole worked on such cases as the Green River Killer, the Elizabeth Smart kidnapping and the hunt for the Unabomber. This and other experience interrogating wrongdoers taught her how to read people.

It also taught her that she can’t eyeball a serial killer or a rapist or a psychopath—no one can. Even if you pride yourself on being a good judge of character, crime stats show that the majority of people are wrong…and often.

In the 1997 bestseller “The Gift of Fear: And Other Survival Signals That Protect Us From Violence,” security consultant Gavin de Becker had some compelling anecdotes about women who smelled danger, owned their fear, and walked away with their lives. Oprah dedicated an entire show in 2008 to celebrating the 10^th anniversary of de Becker’s popular book on how fear can save your life.

As empowering as it would be to have that survival sixth sense, O’Toole makes the case for being prepared rather than jeopordizing your safety by trying to “wing it.” O’Toole is not one to go with her gut. “People are adamant about holding on to the idea that they have exquisite instincts,” she says. “But how many times do you really think ‘I better listen to my stomach and do what my stomach says’? Have you really had success with doing that?”

Your judgment can be thrown off by factors like fear, stress, fatigue, alcohol or drugs, she says. “What if your inner radar was off that day?” O’Toole cites many hair-raising cases she’s familiar with from her time at the FBI. Rather than relying on your fear, what she calls her SMART system (a sound method of assessing and recognizing trouble) is a series of interviewing techniques meant to be empowering. Using the type of questioning she teaches to law enforcement officials, you can learn to evaluate contractors, boyfriends, nannies and the like. “This gives people the ability to be their own profiler, in everyday life,” O’Toole says.

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Scenario 1: You’re hiring a contractor to work on your house. He’ll be there with you and your family, and sometimes when you’re not home.

“Having someone come into your home with access to you (especially if you live alone) and your things is often such a casual decision,” O’Toole says. Instead, treat your first meeting like an interview. “Extracting info and reading people is a process,” says O’Toole. “You want to know if their response to criticism is going to be disproportionate. Is this the kind of person that’s just going to go ballistic?”

Among her interviewing tips: Plan the interview, be calm, and set some goals for it. You want to build a rapport and not babble on, hijacking the interview. Take it slow and “listen between the lines,” says O’Toole. Phrase questions in an open-ended, non-judgmental way: “When you’ve worked with someone and there was a problem, how did you deal with it?” Or “If someone wasn’t happy with your work, how did you deal with that?” If he avoids answers, gets defensive (“Why would you ask me such a thing?”), or changes the subject, take note.

O’Toole suggests writing down your evaluation of a person, and looking for clusters of these troubling behaviors, not just a single incident, and trying to put them in context before you make a decision.

Scenario 2: You’ve recovered from a bad breakup and are ready to date—online.

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Brad’s profile catches your eye right off. He describes himself as “fit and good-looking,” and says, “I’m looking for the perfect soulmate I can love forever, someone who will love and take care of me.” O’Toole writes about the case of William Michael Barber (the “Don Juan of con”) who romanced victims via dating sites, married them, cleaned out their bank accounts, and then disappeared.

However, for would-be daters afraid that every Mr. Right is Mr. Scarypants, experts estimate psychopaths as comprising about 1 percent of the general population. Psychopathy is a personality disorder characterized by a lack of empathy or remorse, and by shallow emotions, among other things. However, they can be extremely charming and manipulative, and have learned to mime feelings in what O’Toole calls “impression management.” They are also, she says, masters at spotting your vulnerabilities.

Back to Brad’s profile. Although it’s unlikely he is a true psychopath, there are other negative behaviors to watch out for. “If you’re going to be online dating, look at the words in profiles,” she says. Look for lots of I/me statements that could indicate narcissism. And, from the above profile, the guy describing himself as good-looking could be a narcissist, she says. (She also points out that his adoring niece might have written his profile.) Plus, your own vulnerabilities can color your perception of him. If you ignore his initial neediness because you love that he’s always calling and texting to tell you how beautiful you are, you might wake up five years later with a possessive, jealous husband and think it’s a sudden change, O’Toole says. Watch for patterns of behavior or hints about how he acted in past relationships. A line like “I’m not a game-player,” is a red flag. Perhaps, she says, someone else has accused him of that.

Questions she suggests asking include: “What are your biggest concerns about meeting people online?” “When you’ve had good dating experiences, how did they go?” “When you’ve had bad dating experiences, how did those go?” She points out that if he blames all bad dates on the women involved, that’s a red flag.

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Scenario 3: Your son Max has made a new friend, Steve, and wants to spend the night. You don’t know Steve’s family.

After buying some time, you need to meet the friend’s parents, O’Toole suggests. Even then, if they “seem nice” and have a well-mowed lawn, that doesn’t mean they don’t have unlocked guns lying around, own a pet cobra, text madly while driving, or have creepy Uncle Biff living in the basement. Get to know the parents. Check local registered sex offender lists and dangerous dog registries (the book has a chapter on such resources). Check out family members’ MySpace or Facebook pages. Visit the house; if you see mounted deer heads, that opens the door to ask about hunting and guns.

Scenario 4: A uniformed telephone repairman is at your front door, but you don’t have an appointment. The last time you let in a repairman, everything went fine—and you don’t want to seem rude.

O’Toole brings up the case of Joe LaRette, who posed as a telephone repairman to get into women’s homes, whereupon he sexually assaulted and/or murdered them. Among the questions O’Toole suggests asking yourself are: Are you expecting someone? How easy would it be for him to push his way in? Are you alone? If not, is there someone there (like a child), you’d want to protect (making you more vulnerable)? Is there a way to verify the person’s identity without opening the door—for example, by calling the company? Does he have anything in his hands that could be used as a weapon?

She says that we tend to think that other people are like us, not looking to hurt others. That’s not, alas, true. Her bottom line advice: “I would recommend not opening the door at all. Anyone with a legitimate reason to be there will leave a note or follow up with a phone call. Although this might seem rude, consider that your safety is more important than whether the company gets the job done that day.”

Know how your mind works! Profiler Mary Ellen O’Toole lists five common ways you undermine your perception of people:

NORMALIZING: finding an explanation for risky behaviors. Example: Your daughter’s boyfriend complains angrily about his job and has been practicing at a shooting range. You tell yourself he’s just letting off steam.

RATIONALIZING: A strange car is parked in front of your house for hours with a man sitting in it. You decide not to call the police because you don’t want them to think you’re overreacting.

EXPLAINING IT AWAY: The parents of a missing child turned that child’s bedroom into an office shortly after the disappearance, O’Toole says. The police had decided they weren’t suspects and explained it by saying that the house was small, and they needed a “nerve center” to manage the search efforts. (The child, says O’Toole, was never found.)

IGNORING: Denial or willful blindness on the part of parents, for example, whose school-age child is alienated and looking up bomb-making online.

ICON INTIMIDATION: Bernie Madoff looked prosperous and had rich and famous clients who swore by him. A nice suit, good grooming, and a smile, not to mention family connections or a good job, can go a long way toward fooling you.

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