As I see it, the best solution would be for everyday people to get a posse together and do the cleaning, backed up by the police. Keeping in mind, of course, that the Constitutional position on government is that the people, by lending some of their authority to government, does not mean relinquishing the power to act on their own behalf.
This would take the cops out of equation as the driving force behind the clean up and I believe this is how it ought to be.
I am also aware, though, that the worst OWS offender camps are in Blue locations, where such a notion would be considered vigilantism, and, therefore, anathema.