Very soft work with a q-tip and water first to get the dirt off because you don't want to abraid the surface by rubbing around dirt. Then once clean, take a very fine cutting polish and a q-tip. If you work at it very delicately you can get a lot of the discoloration out. And keep switching out q-tips for clean ones. You are trying to remove the embedded dirt and grime and don't really want to keep moving it around. Once you go over a small area, flip it over to the clean side, then do some then toss and grab a new one. However, you need to guage if the decal can take it or not. Many can, some can't. You will know within the first few minutes if there is hope. I have had a lot of good lucky with most, but some are just too dry and about to flake off and won't take any work on them.Curious to see if anything can be done to improve the decals. I've been told no many times, but had to try different methods on mine before I agreed they are right. Thoughts?
Listen to this guyBeen there on the rubbing compound taking too much of the paint...especially on these white ones. I am telling you, get you some of this stuff - https://www.meguiars.com/professional/products/meguiars-mirror-glaze-ultra-finishing-polish-m20532-32-oz-liquid. You can really control how much paint it takes with this stuff. It is all I use now. It is what I use on the decals as well. Rubbing compound will eat decals up.