If it’s an industrial wasteland (the implication that it’s full of eyesores) then perhaps these images provide some sort of relief. They certainly look like someone has put a lot of thought and effort into them.
They’re also, to me, more absorbing and engaging than, say, tags which suggest a territorial claim over the space, and by extension have a more sinister and threatening effect.
It’s a fine line though, isn’t it? Some tag work can appear to be very elaborate and considered, and therefore ‘arty’.
I would say that vandalism is more associated with destruction. These images you’ve posted are creative. Sure, they are ‘damaging’ the finish of the building, but if the buildings are rundown anyway, their fabric needs more attention than just a full coat of fresh paint, eh?
That said, though, I’m not so keen on the last two images, and if the ‘artists’ tried out their work on my gable-end, ….. grrrr