The answer to 'hardwood floor smells bad' is that there are several common causes, including pet accidents, spills, moisture buildup, or a bacterial/mold issue. Symptoms may include a musty or sour odor that doesn't go away. Solutions can range from DIY cleaning to professional treatment, depending on the severity and underlying cause.
For minor odors, you can try spot cleaning with a wood floor cleaner, baking soda, or vinegar solution. Addressing any moisture problems and thoroughly drying the area is also important. However, if the smell is persistent or widespread, it may require professional deep cleaning, odor removal treatments, or even floor refinishing to fully resolve the issue.