system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Can a soap be dirty? In a sense that there are still some bacteria living on it.
gpt
Bars of soap do get "dirty". A bar of soap helps clean your hands and body by latching onto grease, dirt, and oil more strongly than your skin does. When you're using soap you're washing away those loose, dirt-trapping, dirty soap molecules.  
A bar of soap does not clean itself, however. A Bar of soap gets cleaned by scrubbing. It's the same mechanical action that you use to clean yourself when you wash your hands, So you should also rinse off the soap bar before you put it back instead of leaving it covered in the soap suds from cleaning yourself.