I did a survey of graffiti in the Anthro building bathrooms versus the Economic Buildings bathrooms as an undergraduate. informal findings 20% of the graffiti in econ was racist none in Anthro was.
Although there were several poems dedicated to the love of elderly women. Both buildings had similar graffiti densities.
I'll say that most of the graffiti in the econ bathrooms at my school were pictures of dicks, writing about dicks or jokes (mostly puns) about grout (the grout thing is big in almost all bathrooms at my school). I don't recall any racist graffiti at all, but it's an almost suffocatingly liberal econ program. There was a crazy right wing econ student who brought an assault rifle to class for a presentation. There were rumors that he was an FBI plant there to 'out' a crazy liberal professor as some kind of commie sympathizer, no one ever got the full story about the incident. The guy did have some sort of FBI connection but weather it pertained to the work he was doing on campus was never made clear, there was defiantly a big cover up operation that people on all sides of the police and school spectrum were involved in. I tried to dig deeper into the incident but was rebuffed and found the people who would talk didn't really understand what happened.