along with the previously-mentioned lemon rinds (orange and lime rinds work, too ), try a somewhat profuse amount of baking soda along with some white vinegar.
flush the sink once the foam dissipates.
as for dishcloth odors, buy a few containers of those Palmolive disposible dish cloths, or buy a lot of bleach... i throw stinky washcloths away when they get an odor...
Yuck..........me thinks the new house will be garbage disposal free. My dad has one out in his kitchen in the garage......that thing freaked me out as a kid. I hated cleaning up out there. Like the jaws of life going to snatch me up .....no chew me up and spit me out into the city sewer. Not something I'll require for the new house.