Should a fresco painting like this be left as such with the graffiti overpowering the original beauty of the art work, or should it be treated meticulously subduing the damage bringing out the original beauty of the painting?

We find so many historical sites in India where such heartless damage is done by some irresponsible citizens among us. Being a conservator, i feel that at least at some places of extreme importance such graffiti must be filled up carefully following the basic ethics of conservation. But, departments of culture of different states might take different view on this. At some places they did not give much thought to how much can/should be done and how much should be left just as it is.

It would be nice if we can start a dialogue regarding this.