Most people rarely lie and therefore operate with a "truth bias," assuming others are also being truthful. This cognitive default, while efficient for most interactions, becomes a major vulnerability that people with dark personality traits exploit. They can lie frequently because it rarely occurs to others to question them.

To truly understand a potential partner, look at their friends. A person is a "mashup" of their closest companions. The caliber of their friends in terms of kindness, social behavior, and success is a fantastic and often overlooked indicator of who your partner really is and how they will act in the long run.

There is no single giveaway for lying that applies to everyone. The key is to first understand an individual's normal pattern of speech and behavior (their baseline). Deception is revealed through deviations from this norm, such as adding excessive, unnecessary details to a story to bolster its credibility.

People are practiced and guarded during formal meetings. To understand their true nature, Negreanu suggests engaging with them in informal environments like a meal or drinks. This disarms them, making their reactions more authentic and revealing.

When evaluating people, pay close attention to minor behaviors. A small act, whether cutting corners or showing kindness, is not an isolated incident but an indicator of a person's fundamental character that can be reliably extrapolated to high-stakes situations.

Trust isn't built on words. It's revealed through "honest signals"—non-verbal cues and, most importantly, the pattern of reciprocal interaction. Observing how people exchange help and information can predict trust and friendship with high accuracy, as it demonstrates a relationship of mutual give-and-take.

In a world of transactional relationships and fleeting reputations, the only reliable filter for character is time. Look for individuals who have maintained the same close team and friends for decades. This longevity is a strong signal of loyalty, integrity, and trustworthiness.

Negreanu suggests we're born with the ability to read people but learn to distrust it. He practiced by observing strangers in public, creating stories about them, and then at the poker table, looking for behavioral patterns (like gum chewing) that correlate with bluffing or truth.

Manipulative individuals often betray their intentions through "danger zone" cues they cannot control. These include lip pursing (a universal withholding gesture), physically distancing from a statement, and a significantly increased blink rate, which indicates the high cognitive load associated with deception.