The drain, and plug of kitchen sink can get quite funky.
Studies confirm high bacterial counts (comparable to a toilet) no reason to think disposal any "cleaner". Disinfect: run cold water for several minutes; pour 1- 2 cups of chlorine bleach into drain, let sit for 10m, hot water for 2m; disposal?: turn it on during flush. 2x/wk. Clean out debris daily; plug in dishwasher; liquid soap.