Make you a bet. Every public, commissioned graphic mural ( and Chip Southworth's illegal ones ) in this area has been tagged by vandals. Because these are photo based and not "street art" it may take longer, but I hope that the artists cover their work with a graffiti barrier so that the tags can be removed without hurting the underlying art murals.
Ask Olgilsby and Thurston.
Gotta love the streetcar photo!