The effectiveness of any deterrent is directly related to how long after the tagging session the graffiti is removed. Generally it has been found that taggers take delight and gain momentum from apathy to their activities.
The faster the graffiti is removed and with the least fanfare as possible, the less satisfaction they get from their actions.
The idea of a good deterrent is to make it cheap and quick to get rid of the offending graffiti and to do so without making a big deal about it…
Getting their art on the news only fuels their ego.