Graffiti have existed since ancient times, in fact we can find examples dating back to Prehistory, Ancient Egypt, Ancient Greece, and the Roman Empire. In those ages they were considered art’s expressions and they usually were full of natural or social meanings, such as a good omen for the harvest or an expression of Egyptian Gods’ powers.
Nowadays the situation is a bit different. I personally think that in most cases graffiti are still the same as in the past: a pure form of visual art that can express immediately, with the strength of colours and images, social, political o different themes. Moreover, they could be a solution to adorn the landscape, in particular to make devastated buildings more appreciable.
However, on the other hand graffiti have to be considered vandalism when people create them to disfigure monuments or other buildings, representing pictures without meanings or purposes.
So in conclusion, I think that it’s fair to punish the creators of “no sense graffiti”, but it should be allowed even better consecrated this type of art when it is used, with the property owners’ consent, to beautify a city, to tell its history or just to communicate something to citizens and tourists.