if u use wd-40 ur gonna need rubbing compound afterwards. ur best bet is 3M adhesive and tar remover(clear coat safe). i've used it several times, on paint, windows, and even my ***...

 

I debadged my 03 VIII over the summer finally starting to fade but if I look real close I can still see really faded text, looks like mitsu threw on the badge then clear coated maybe?

 

Maybe The Paint Behind the Badge when it was on did not wear off by the sun and now the mark is there

Thats my take

 

I had a similar issue.... the lettering was gone after goo off and some light scrapping, but the diamond symbol was always ghosted.

get some of the meguiers (spelling) scratch off.
I was a friends house and he slapped some on, instally gone and I have yet to see it back (15+ car washes since) I saw some at Lowes and oriellys/schucks

 

rubbing compound or even scratch/swirl remover would probably work best because it will actually remove microscopic layers of clear coat...this will "accelerate" the natural erosion that created the difference in appearance in the first place. Not sure if it will actually work, but it theoretically makes sense. Oh and u will need some sort of power tool to achieve maximum effect of the rubbing compound...needs to be brought up to heat. I use a simple power drill with a foam pad bit, but a proper buffer will be safer and produce a better finish

Edit: on second thought you can probably use the scratch remover by hand...but those compounds work best when the area becomes slightly heated by friction...so rub fast lol

 

Yeah, I used Meguirs Scratch-X on drock's car, worked great.