I wouldn't try it on clear plastic as it may fog. I know it is good for metal parts. For rubber, vinyl, paint, and other materials I can't see it harming it but don't see it doing any good either.
guys at work use it to clean just about anything. I spilled a quart of primer on a concrete floor and wd40 cleaned it up, got every drop off the floor.
One thing that the guys at work caution about is using it on o-rings, it might eventually make them go bad and you will have to replace them.
It is an excellent cleaner and adhesive remover. I wouldn't use it on rubber, wood or clear plastics. Use silicone spray on those. I'm not sure if WD40 contains any silicone, but if it does, don't get it down the intake on any modern vehicle. Silicone will sour O2 sensors and can sour catalytic converters.