Plastic is a very strong and durable material that is sometime safer than glass when used in a variety of different objects. Clear plastic can sometimes become cloudy for various reasons. While cloudiness due to scratching cannot be cleaned away, cloudiness from staining or stain build-up can be repaired with the proper materials. Cleaning foggy plastic can normally be done quickly if the fogginess isn't too severe and the plastic itself is not damaged.
Pour warm water into a spray bottle and add white vinegar in a 50-percent solution. White vinegar is a very strong natural cleaner that will not damage the plastic.
Spray the plastic with the vinegar solution and allow it to sit for a minute.
Wipe the plastic with a lens cloth. Lens cloths are designed to be soft enough to avoid scratching while also providing enough friction to remove residue and other stains. You can scrub heavier plastic with a sponge.
Repeat until the plastic is clear again.
If the vinegar is ineffective, try an ammonia-based glass cleaner, then reapply the vinegar solution afterward. Plastic that is foggy due to scratching must be sanded to restore its clear finish.