Why would a person be called a blabbermouth? Is that good or bad?

A person might be called a blabbermouth if they have a tendency to talk too much or talk without thinking. It is generally considered a bad trait because it can reveal secrets, spread gossip and rumors, and leave the blabbermouth vulnerable to saying something inappropriate or offensive. It can also be disruptive to the flow of conversation and can make the blabbermouth appear to be unprofessional or immature. Blabbermouths can also be seen as annoying or unreliable, as they may talk too much or say things without considering the consequences.