If you asked a random stranger what their opinions on graffiti were, i guarantee 90% would say something negative. Even within the exploration communities most people i know get frustrated with the presence of graffiti, to a certain extent i do to, but not all the time.
Most if not all of the hidden spaces in the London underground are plastered with the scribbles of previous visitors, usually Tox and Cut. Two taggers who in fairness you have to respect for their ability to gain access to the aforementioned spaces, some years before we set foot in them, but at the same time, hate the fact they have absolutely zero creative or artistic ability.
Arsenal, much like the rest of the Parisian ghost stations, is some what different to London. Sure you still have the walls sprayed by those whose biggest accomplishment is drawing a somewhat correct looking penis, but you also find various sketches, stencils and pieces. Bright, six foot high, vivid and detailed works of art. These i tolerate, and in most cases enjoy. People like this are the true champions of the metro systems, for the simple reason that they have the balls to stay in the danger zones for as long as it takes.
Arsenal closed during WW2 on September 2, 1939, and never reopened.