I scrubbed off the graffiti from my brick wall. However, I couldn't get it all off. Now there's more graffiti. It's important to remove all visible traces of graffiti from unpainted surfaces. Graffiti should always be completely removed.
Pressure washers are available at several locations.
Try darker colors. Graffiti doesn't show up well against a dark background. I've noticed problems with graffiti in the business district where I work. The City of Seattle has a Graffiti and Litter Matching Fund available to fund ideas that will reduce litter and graffiti vandalism in business areas. If you are interested in painting out graffiti yourself, we can get permission from property owners and provide the paint and equipment.