Instead of razor blades, which in a moment of inattention, can cut the filon, or in the case of a painted automobile the paint, I recommend a product that I discovered many years ago and use more often than a razor scraper:
ScrapeRite plastic razor blades
They now come in several "strengths", but, I find the yellow ones the most useful. They are great at removing caulk and stickers without damaging the base surface. I discovered them many years ago when auto dealerships started putting their advertising on the cars with those adhesive letters (they look like paint, but, are actually adhesive letters). I don't like "free advertising" for the dealers, but, rapidly found out that a razor blade will take the clear-coat off without any resistance at all...enter the plastic razor blade. Flexible and soft enough to follow a contour without damaging it, but, sharp enough to peel the caulk or label right off.
Another lesson learned many years ago...be careful what adhesive remover you use to loosen the adhesive. Many of them will attack plastics, dissolving the gloss layer, sometimes the plastic itself and some will even soften paint. The best adhesive remover I've found is made by Girot's Automotive:
Girot's Adhesive Remover
Many years of trial and error, and this is the best at removing the sticky mess without damaging whatever is the base material. It is the only remover I keep handy; inside the sticks and bricks, in the RV and in the garages that I have around the place. Will also remove tar, dried grease, pine sap, etc. and not damage the paint. It is the only thing that I'll use on my antique cars.
Heat will work, but, depending on the gun (mine will get up to 1800 degrees), heat can also damage the underlaying material if not use carefully. Keep it moving so that you avoid hot spots; the trick is to get it hot enough to soften the adhesive and not anything more. There is a lettering company for trucks and the like in our little town and I've seen their guy use a torch; many years of experience behind that technique!
