Plastic is prone to staining. The result can be unpleasing to the eye and, in the case of plastic dishes, downright unappetizing. If you are tempted to throw them away, stop. Even the most set-in stains are not impossible to get out. With a little effort, using cleaning agents you already have on hand, you can have pristine plastics again.
Scrub the plastic using water and a mild detergent. This alone may remove the stains if they are food-based and relatively new.
Fill a sink or basin with soapy water and a little bleach. Allow your plastics to soak. Rinse very thoroughly after soaking.
Apply rubbing alcohol to set-in stains and allow it to stand. Pour a mixture of white vinegar and water onto the stain and allow it to stand for a few minutes.
Mix baking soda and water together to form a paste, using a sponge to scrub it into the plastic.This is particularly effective for oil stains.
Try setting the stained plastic outside for a few hours. Exposure to sunlight can help fade stains.