A lot of how easy/difficult decals are to remove depends on several things:
What type of decal is on there?
How long has that decal been on there?
Was it on the sunny side?
How much graffitti has been scratched into the decals? Etc. Etc.
The coleman decals have some colors that peel right off, then you get to some of the other print on them that dont peel well, and the adhesive removers dont penetrate the vinyl. So you first need to get the vinyl off, then use the removers for the remaining glue? The older they are generally the more difficult to remove. Any event they are not fun to do! Some projects I dont mind doing, some I avoid like the plague! Decals are a plague!