I don't have a very strong opinion towards graffiti, though some of them are really cewl. Usually I don't give a damn if they appear on houses in the city or wherever.
But I found out that I find it rather disturbing to use toilets which have been decorated with the stuff.
I love to go to the toilet and I do it on a regular basis. It's important to mention that the toilet is not just a place to rid yourself of redundant bodily fluids. It is most importantly a place to withdraw to when it all seems to be a little too much all of a sudden when you're out with friends, or working really hard, or whatever. Sometimes all the impressions of real life are just overwhelming and then you need a little space. And then there it is, your rescue space, and you wish to enjoy the nothingness and just relax a little, only someone else thought it would be interesting to add something to the otherwise so delightfully boring walls.
*argh*