Adding a point of information as someone who has been extensively involved with the Occupy Boston camp, the spy games players (the undercover/plainclothes other than those at marches, the intel people, the federal agents, etc) have been, IME, the subset of police most engaged in problematic behavior. The uniformed cops on Atlantic Ave Thursday night were our rank-and-file regulars - ordinary cops who are regularly on the Occupy Boston detail. They know us, they know we're not monsters (and we know it of them), they like most of us well enough. I find it quite easy to believe that there was an undercover being an asshole provocateur at the same time as our regulars were showing friendliness, decency, and restraint.