Yes, graffiti can be considered art. If so, the question might then be asked, by what standards? The answer is, there are no standards anymore.
The classic definition of art, over the centuries, was rather rigid. It encompassed evocative emotions of form, beauty, esthetics and competence. With the evolution of so-called modern art, the definition of art had to be broadened to include contemporary tastes.
Not to long ago, we had the the bizarre paintings of Dali, and the commonplace stuff of Warhol. Again, we were asked to elasticize the definition of art, and to be more open in our tastes. All well and good.
Eventually, we come to graffiti. Considering the trend line, it would be difficult to rule it out. However, it is important to note that just considering something as art, does not make it a work of art. It may be difficult to define art, but to modify an old quotation, we know it when we see it.
Under that point of view, graffiti can be called art, but it sure as heck doesn’t look artistic.
Dick Brooks