Dirty soap can't clean itself, though. A contaminated bar of soap gets cleaned via the same mechanical action that helps clean you up when you wash your hands: good ol' fashioned scrubbing.

Can bacteria live on soap?

Yes. When you wash your hands, you transfer a thin film of bacteria, skin flakes and oils to the bar of soap. A 2006 study of 32 dental clinics found bacteria growing on the soap in all of them – after all, standard soap doesn't kill bacteria, it just dislodges them.

Does bar soap get you clean?

In general, bar soap cleans by physically washing away dirt and microorganisms, according to the Centers for Disease Control and Prevention (CDC). Compounds in bar soap called surfactants work to physically remove germs and debris as soon as you add water.