If you've got a smelly drain, there's probably bacteria growing in it.
To eliminate the problem, start by mixing a cup of baking soda and a cup of vinegar. Pour the mixture down the drain, let it sit for 15 minutes or more, then run the disposal and rinse with hot water.
To clean disposal blades, freeze white vinegar in ice cube trays and let the disposal grind away at them. The ice will help dislodge stuck-on debris, and the vinegar freshens the unit.
If there's still an odor, try pouring in half a cup of bleach, but not if you have a septic system. You may need to go buy a live enzyme product that eats away bacteria, or a corrosive cleaner meant to unclog drains.
If your sink's drain plug has moldy buildup, soak it in a vinegar or bleach solution, then wipe away any remaining grime. If mold builds up again quickly, replace the plug. Home improvement stores should offer styles that fit your sink, and some even stock scented versions.
If unpleasant odors continue, consider whether you might have a backed-up disposal or clogged plumbing.
The crunching and gnashing of your disposal may make you leery of touching it, but there are ways you can keep it running well without calling a professional.
DeSilvia says to always run cold water before, during and after using the disposal.
"Never use hot water with your garbage disposal," he says. "It breaks down food, causing it to liquify and accumulate around your pipes."
It's best to scrape large pieces of food into the trash can, then let the disposal take care of smaller scraps. Don't put potato peels, shellfish, coffee grounds or other fibrous foods into the disposal. They're clog-makers.