Well, graffiti 'artists' like it. But their opinions don't count much. Train robbers like robbing trains too.
Back to graffiti, we have to ask ourselves why we hate it so much. It's annoying, illegal, and can make otherwise nice places look like dumps. When we see it, we rage inside. Why, we wonder, would anyone waste their time with such a thing? Who, we ponder, might this Vegeta person be? And what, we muse silently, can we do to stop him?
You can hope to stop defacers in the act by attempting to be in the right place at the right time, but unless you're armed with something stronger than harsh language, you may find yourself alone and freshly mocked. There's nothing less threatening to the average criminal than the phrase "Hey, you! Cut that out!"
Alternately, you can fill out a Graffiti Report form that the city of New York has so kindly made available to us. I have no personal experience with the effectiveness of said report, but in the best case scenario, someone comes along a couple weeks later and makes a new blank sheet of paper for someone to tag.
Or you could accept the fact that, like jaywalking and music piracy, graffiti is here to stay.
There's an upside to this. Qualified acceptance allows us a measure of control. Why should we be content that the surfaces throughout Kensington be covered in meaningless scrawls? If we must have it, then we should demand the best. Let the journeyman can-wielder drift down to Midwood to ply his lesser craft. In Kensington, we should settle for nothing less than art. This can be accomplished by fillling out this Graffiti Report Card and taping it up next to local defacements. If we can't stop them, we can at least shame the bad ones into leaving the best urban easels open for their betters.