I just know anytime I've used it on external car plastics it will look good for a while, but then the plastic will get this faded milky hue to it.
True. Silicone based cleaners like Armorall or oils, waxes ect. aren't cure alls, after a while they fade away due to exposure and the oxidation of the plastic occurs again. You can in theory keep using them and it will diminsh further and further over time, but it's a pain to repeat every couple of months for years. It's a reason that some motorheads won't use it on their cars (once you start you can't stop, and older and cheaply made plastics will discolor according to some car forums). Without going into chemical detail The plastic itself has a lot to do with the oxidation of the item.
I've used armor-all and polishes on my systems with no problems thus far.
I'm unaware of anyone having an issue with them so far.
But it would be useful to me if anyone that has post about it here. I've done quite a bit of research on plastics for my masters, and it continues to be something Im very intrested in.