A mop, just like any other fabric cleaning tool, will develop an unpleasant odor over time, typically as a result of moisture and residue that lingers on it after you're finished cleaning. The odor will only get worse with time, so it's best to clean and deodorize your mop when you first notice a foul smell developing. A simple homemade remedy can rid your mop of stinky smells.
Rinse the mop with clean, hot water then wring it out. Do this immediately after each use of the mop to wash out residue you collected while cleaning. Wringing out the mop prevents mildew growth and speeds up the drying process.
Fill a bucket with equal parts of water and white vinegar, for odor that has been lingering for a while. Soak the mop in the solution overnight. The vinegar will disinfect and deodorize the mop.
Rinse the vinegar solution out of the mop with hot water and wring out the mop.