The answer to 'garbage disposal foul smell' is that a smelly garbage disposal is typically caused by rotting food or bacteria buildup. This can lead to unpleasant odors coming from the sink drain. The most common symptoms are a rotten egg or sewage-like smell coming from the disposal.
To address this, you can try a few DIY solutions first. Run the disposal with hot water and baking soda or vinegar to help break down and flush out any debris. You can also use a disposal cleaner product designed to remove odors and buildup. If the smell persists, it may be time to have a professional plumber inspect the disposal for any deeper issues that require repair or replacement.