What kind of guy is a smarmy guy? Meaning?

A smarmy guy is someone who behaves in a self-serving, overly friendly, and often insincere manner. They often use charm and flattery to gain favor with others and will often use manipulation and deception to get what they want. They may come across as very confident and charismatic, but underneath this façade, they are often insecure and lack genuine empathy for others. Smarmy guys may use their charm to make people like them, but they often do not have any real interest in having meaningful relationships. They tend to be selfish and often take advantage of others for their own gain.