I finally got around to reading The Sociopath Next Door. I wish I had read this years ago. It's a must-read, and I encourage you to pick up a copy. In The Sociopath Next Door, the author states what she believes is "the most reliable sign" that someone is a sociopath:
[T]he best clue is, of all things, the pity play....
[G]ood people will let pathetic individuals get by with murder, so to speak, and therefore any socipath wishing to continue with his game, whatever is happens to be, should play repeatedly for ... pity.
Sociopaths have no regard whatsoever for the social contract, but they do know how to use it to their advantage. And all in all, I am sure that if the devil existed, he would want us to feel very sorry for him.
When deciding whom to trust, bear in mind that the combination of consistently bad or egregiously inadequate behavior with frequent plays for your pity is as close to a warning mark on a conscienceless person's forehead as you will ever be given. A person whose behavior includes both of these features is not necessarily a mass murderer, or even violent at all, but is still probably not someone you should closely befriend, take on as your business partner, ask to take care of your children, or marry.
The Sociopath Next Door at 107-109. That observation is spot-on. Anyone who has represented criminals knows that most of them beg for your pity. "I am being railroaded!" Even child molesters say this.
Watch "To Catch a Predator." Every person who went to a house to have sex with a twelve-year old girl starts crying: "My life is over." While, in many important ways, that's true, it's not like it is "over" for no reason. Yet, almost to a person, the first thing these would-be child perverts do it beg for pity.
The best "tell" I've discovered is shamelessness. In a sense, this is tied to pity. How can a person who just beat up his wife beg for pity? How can a person who ate himself into obesity sue a fast food restaurant? Have you no shame, at long last?
When my dog does something really bad, he bows his head in shame. Once, he hid from me. He didn't even feel worthy of being with the family. No dog craps on your carpet and then smiles and licks your hand. Lots of people do much worse and then are so lacking in shame that they return to do it again. Avoid these people.
Incidentally, the author notes that a lack of shame is something that characterizes a sociopath. When imagining a sociopath:
Imagine no struggles with shame, not a single one in your whole life, no matter what kind of selfish, lazy, harmful, or immoral action you had taken.
Id. at 1. So if you know someone who has no shame and who always has a sob story for you, run away.