But, really, why paint that on a door? Does the writing pass that door every day, or at least frequently? What do people think when they see that, which is on a side-street that's not terribly well traveled, either by vehicles or foot traffic? What, if anything, would the writer accept as an answer to the question? What else has the writer put up?
Yes, it's easy to dismiss it as vandalism. But not so easy to understand the confluence of this that and the other that resulted in those markings being in that place at that time.