Within the economics and law fields, many decisions must be based on what is reported by another person, who can deceive the decision maker by lying. Thus, discovering if our interlocutor is sincere or not is crucial in order to make good decisions. Research highlighted that the spontaneous strategies that we use to identify possible lies are often misleading. Our moods and personality, together with the level of trust between speakers, are all factors that can influence the detection of lies. However, the ability to discover lies may increase with appropriate training and experience of dealing with people in contexts where the probability of being deceived is quite high. Regardless of our actual skill in discovering lies, our attitude toward lying can influence the decision-making process. For example, when we are aware of the possibility that a lie occurs, a suspicious attitude can lead to a wrong judgment. Similarly, perceiving an alleged lie, whether it is real or not, can prompt the use of emotional heuristics linked to the perceived feelings of antipathy, anxiety, or anger. This can lead to decisions aimed at creating disadvantages for the partner. Under these circumstances, it is necessary to take into account the variety of human behavior, not relying on stereotypes to identify a lie. Being used to interact in particular contexts where the risk of being deceived is high may definitely help to sharpen the ability to find out who is lying to us, increasing the likelihood of taking rational choices based on reliable cues.