The answer to 'garbage disposal foul smell' is that a smelly garbage disposal is usually caused by a buildup of food waste, bacteria, or mold. Common symptoms include a persistent, unpleasant odor coming from the sink drain. The good news is that this is a common issue that can often be resolved with some simple DIY maintenance.
First, try running the disposal with hot water and a degreasing dish soap or baking soda and vinegar to help break down and flush out any trapped debris. You can also grind up citrus peels or ice cubes in the disposal to help scour the blades. If the smell persists, the disposal may need a more thorough cleaning or even replacement of the disposal unit. If you're not comfortable doing this yourself, it's best to call a professional plumber to diagnose and fix the issue.