Originally Posted by dbworld4k
Hmm, it works even for blobs that are a few years old?
Yep! You just need to keep rubbing and it'll start levelling them off.
The small problem you'll run into with the product if you have to rub for a lengthy amount of time is that it can make the clearcoat surrounding the levelled blob cloudy. The cloudiness comes off with a cleaner wax, and is far less dangerous (and far easier to remove) than the scratches caused by sanding.
Another problem which you can face (with either method) is the removal of the metallic flake in your paint. When you paint a car with metallic paint the flakes tend to float to the surface, and if you don't put a layer of clear over the (recessed) flakes to form the bump you'll be removing you'll end up with a flat spot of base colour.