And here's how you do this without getting arrested.
Speak to the owner of the property, mention that people are posting offensive and inflammatory material on their property and offer to remove them. It's worked for me before, just hunted down the person who was responsible for the management of the building and described what someone had hung up. Offering to do it yourself means it doesn't cost them anything.
But hey, she's fucking 80, and pretty much right. Fuck these guys.