The clear paint protector patches that Lexus applies in front of the rear wheel wells on the 6th gen ES darken with age. They turn black. The look awful, especially on white and light colored ESs. I have a 2013 ES with this problem. My car is gray, so the "black" doesn't stand out as much as on a lighter colored car. But - I found a great way to fix it.

1) Use "Scratch Out" from Formula 1. Rub for about 3 minutes. Reapply until black is gone and your cloth is clear. You can buy this at Walmart.
2) Wax with Mothers Reflections Top Coat.

I just did this yesterday and was amazed at the result. See before and after pics below.

 

Looks pretty good... You could also probably use the solution for cleaning the clear headlight covers...

 

Good trick. Imagine what the door would look like if there wasn’t a protector on there!

 

Update 11/2023 - 10 months later and the protectors have turned black again. Also, due to our first summer in south Florida tge sun fried them and they have cracked. The steel expands with the strong sun, and the 10 year old protectors are now more brittle and crack.

I uaws plasric razor blades and 3M adhesive remover to take these off. It comes off without much work, and the paint is perfectly new under these.

 

Did you heat it up first?

 

No need to heat it up. Just start with the plastic razor blade. Remove what you can with that. Then adhesive remover to get off all the glue. Then scratch off to polish it.