There isn't a spot in my mom's house that she doesn't clean, disinfect, tidy or otherwise sanitize. The sink drain is no exception. Sometimes, it can be the source of unpleasant odors but there's only so far you can reach in with a scrub brush.
If you've got a garbage disposal in working order, you're in luck. The next time you eat an orange, you can ward off scurvy and give your sink a light citrus scent. Toss the peel down the drain and run the disposal with hot water for about thirty seconds. It'll be one less mystery smell to rid from your house using an au naturel source.