It's true that not every person who claims to be a Christian is dedicated to following Christ. Nonetheless, the fact that someone is willing to take the title out loud in the presence of another person is a good place to start.
Now ideally, if someone says that they are a Christian, it should mean that they do what Jesus said: to help the poor, treat the sick and injured, aid the oppressed and those in jail, refrain from violence and anger, educate others and preach the gospel.