The answer to 'vacuum smells bad' is that a smelly vacuum is usually caused by a buildup of dirt, dust, and debris in the vacuum's interior components. This can lead to unpleasant odors, especially if the vacuum has not been properly maintained or cleaned.
Some common causes of a smelly vacuum include a full or clogged dust bag, a dirty filter, or a buildup of pet hair and other debris inside the vacuum. In some cases, the vacuum's motor or other internal components may also contribute to the unpleasant smell.