When you think of a “sociopath,” chances are you think of a serial killer or a con man in a movie. But chances are you've met a sociopath — after all, according to Harvard psychologist Martha Stout, author of The Sociopath Next Door, one in every 25 people is a sociopath.

With so many alleged sociopaths around, and with their charming nature, it can be hard to know one when you see them. INSIDER spoke to experts about some tell-tale signs that the one you love may actually be a sociopath.

They charm the pants off of everyone in the room.​

A standard trait of a sociopath is that they are charming and gregarious people. They know exactly what to say to everyone to get them to like them. That's probably why you were drawn to them in the first place.

“They typically know how to woo a person using incessant flattery and compliments,” psychotherapist Patti Sabla told INSIDER.

Be careful: Because a charming people-person isn't necessarily indicative of a sociopath, you should look out for other signs, too.

(Getty/iStockphoto) (Getty Images/iStockphoto)

They disregard your feelings.​

Sociopaths lack empathy so if you get upset with them, they have a hard time understanding why. They won't act sorry or even see a reason for you to be upset.

“They may get drunk and do something awful like tell off your mother or your best friend,” Sabla said. “When you confront them about it the next day they don't care. They are incapable of empathy and may even try to blame you for 'trying to make them feel bad' about the situation.”

You don't think even they believe what they're saying.

Do you ever get the feeling that the person you're talking to knows what they're saying isn't true? Sociopaths are skilled liars, but sometimes they're so disingenous that their actions and facial expressions give them away.

“You feel a weird sense that he’s not really believing his own words,” Carlos Cavallo, a dating and relationship coach, told INSIDER. “Like they will tell you they love you, but their actions seem almost dissonant with it.”

They lie constantly.

Sociopaths are compulsive liars because it's in their nature. They lie to make themselves look good.

They're also really good at it.

“Sociopaths can make up a blatant, outrageous lie without a blink of an eye with the drop of a hat,” Sabla said. “Their lies usually are self-serving, making them out to sound really impressive.”

(Getty) (Getty Images)

You can't seem to stay mad at them.

Even if you do catch them in one of their famous lies, you can't seem to be mad at them for long because a sociopath will charm you out if it.

“They have a smooth, fast way of dealing with people that you might even mistake for real charisma,” Cavallo said.

They don't have many (or any) close relationships.​

Sociopaths are the life of the party, so plenty of people will know them and want to be around them. But sociopaths tend not to have a lot of real friends because of how self-involved they are and how often they hurt people.

If a person has a lot of burnt bridges and no real, close friends, they just may be a sociopath.

You feel like you're the only person in the room.

When you're in love, you might just feel like you're the only two people in the room. But if a person puts a creepy and unnatural amount of focus on you, then suddenly leaves you, they might be a sociopath.

“They’re with you seemingly non-stop,” Cavallo said. “It’s almost consuming, until you run out of steam on their latest manic binge, and you’re left in the desert for a while.”

You can't count on them.​

Sociopaths are so self-involved that they will frequently forget things that have to do with other people. They will flake on people, forget things, and disappoint you. They won't take responsibility for it either.

(Getty istock (Getty istock)

They can't hold down a job.​

Sociopaths are sometimes terminally unemployed. They can't seem to hold down a job because of their attitudes and will blame it on everyone but themselves.

“They are so antisocial they burn their bridges at work and blame everyone else but themselves for their inability to succeed,” relationship coach and matchmaker Bonnie Winston told INSIDER.

You get blamed even for their faults.​

Saying 'I'm sorry' is not always easy, but sociopaths find it nearly impossible to admit they're wrong. They will always find a way to turn it around on you.

“For example, you ask them to pick you up from work at 4:00 p.m. When 4:30 p.m. comes and they don't show, you call them to find out what happened. They blame you for 'not reminding them because you know they are forgetful.' Then they try to guilt you for even asking them in the first place 'knowing how busy they are,'” Sabla pointed out.

They're spending your money.​

Sociopaths feel entitled to what is yours, so they will know how to spend your money, psychotherapist and professor Nicki Nance told INSIDER.

If someone is way into you picking up the check or has no problem using your credit cards, they might be a sociopath.

They don't seem to know what makes you upset or why.​

A good partner will know your triggers and do their best to avoid hitting them. Sociopaths seem to have a goldfish memory and can't seem to remember what ticked you off last. They just can't grasp that people have complex feelings.

“This will come out of his or her psychological issues, but will resonate as an overall feeling of strangeness in the way they handle their affairs with other people,” Cavallo said. “A strong feeling of disconnect will plague you.”

They want to seek revenge.​

Sociopaths are generally known as charming, but if you cross them, you'll know why they don't keep people around for too long. If they feel they've been betrayed or lied to, they will go to sometimes extreme lengths seeking revenge.

“If they feel they have been embarrassed or humiliated, they will remember that,” Sabla said. “Without anyone knowing it, they can be plotting revenge for days, weeks, or even months. They won't let it go until they feel they have 'gotten even.'”