Clean with an organic acid like lemon juice or vinegar.
Most often those horrible smells are proteins. Acids are good at breaking up proteins.
Hydrogen peroxide can work too, it oxidises organic matter.(but i prefer using the citrus). You may have to soak it for a while to really let it work. You can do this by soaking paper towel, or toilet paper in the acid cleaning solution and sticking it to the inside of your bin. Spray it a little more so its drenched and leave it for a few hours or overnight.
@MartinTheFirst i have a favorite cleaning agent made from citrus oils. This stuff is like chemical warfare on proteins. Ive used it on milkshakes soaked into carpet, in bathrooms and toilets where kids 'have messes' , its amazing! Its my 'last resort cleaning agent....as it isn't cheap.
It also gets off paint, removes permanent marker, deters rodents and ants and leaves a strong citrus smell .
If you can find it, or a similar product , its worth its weight in gold.
