Graffiti

Why is it that people who graffiti always have neat handwriting? In fact they nearly all seem to have the same handwriting! It's lovely, neat, swirly, confident writing, just such a shame most artists can't spell.
I don't think there is that much graffiti around Plumstead Common and Shooter's Hill and I am convinced it must be magic paint on the boards up around the old Prince Albert Pub as any graffiti on there seems to just slip away.