[hussong]

Not a lawyer either, what I've read about street art in Germany is basically: if it leaves residue (physical changes your object) = property damage, if it's easy to remove without a trace = no case.

Which is why a lot of street artists swapped the can for painted paper and water-soluble glue.

Or, related to cars: hard to remove stickers = property damage, some chalk on the tires or shaving foam on the hood = no case, deal with it.