For as long as I can remember, every few months the garbage disposal would start to stink. I tried everything. You know, like grinding up egg shells, bleach, baking soda, etc. If it did wok, it would only be for a short time.
A couple of years ago I did a long search on the web for ideas. There were plenty, but nothing looked good. Kind of like people were making stuff up without knowing what they were talking about.
Then I ran onto a comment by someone who seemed to know what he was talking about. Now after a couple of years I can say that he did have the solution. The problem is that garbage gets stuck to the inside and is not washed off. Then rots.
Start water and disposal before pushing the garbage into the disposal.
Then letting the water and disposal run for 5 to 10 seconds after the garbage is ground up, washing the inside.