Whoa. Wikipedia has a regular Juggalo page and then a page specific to Juggalos as a gang: http://en.wikipedia.org/wiki/Juggalos_(gang)
It asserts that 10-15% of Juggalos are criminals, some with ties to the Bloods and Crips.
“According to the National Gang Intelligence Center, there are more than one million self-proclaimed Juggalos across the United States. It is estimated that 85–90% of self-described Juggalos are peaceful, non-criminal music fans. The other 10–15% make up the Juggalo subculture’s criminal element, which has been linked to numerous crimes including extortion, murder, domestic terrorism, drive-by shootings, drug trafficking, arson, burglary, home invasion, armed robbery, aggravated assault, and weapon offenses, and has been documented collaborating with a wide array of street and prison gangs.”
Most of the references seem to come from National Gang Intelligence Center and sites like publicintelligence.net.