A slave is set to a task by their master for a reason– their purpose for even being alive. Slaves face great difficulty everywhere they go. Escaped slaves are often on the run if not from their former owners, then certainly from the law. Few are educated or have any practical experience to make a way for themselves. Most have limited social skills which give away their social status. Slavers may notice freemen as "unclaimed property" and try to "claim" them as slaves. People sense a sort of "inferiority" about slaves and freemen, and they will likely either ignore you or boss you around. Many freemen turn to crime to make ends meet and so anyone who doesn't assume you a slave immediately, will likely assume that you are a criminal. If you can ever really leave the slavery mindset knowing what it's like to be a slave, then you can pose as a slave with little difficulty and without raising much suspicion. People seem to do things in front of you that they would normally only do when they are alone.
belong to their masters and cannot openly make the decisions that they want to, their destiny is defined by the wills of their masters. Your actions are decided by your master, and you serve his ends. You may be a "star" slave and actually make a statement to your master, or your life may be nothing more than serving a pointless end. If you are an unlucky slave, then your life will be for nothing more than fighting a lost campaign or treating a person with no power as an exemplar. If you are a lucky slave then maybe you can see escape without slaughter, or even talk to your clients and perform some subterfuge.