Well when I helped start the university occupation movement that preceded Occupy, we had shockingly intense surveillance, infiltration, and intimidation tactics used against us.

I handled the technical side of everything. Taught people to leave their phones at home during meetings, we used gpg, issued secure laptops, met in random locations at random days and times, had tamper evident secure rooms with air gapped databases for our contacts and meeting minutes, etc. It was fun engineering challenge for me.

Yet we had one member have her house broken into by masked men with AR-15s. They threw her out of her bed and threatened to kill her unless she told them who our leadership was. Then they interrogated her for an hour before leaving. Never identified themselves. One of our fundraisers was broken up with flashbangs and teargas.

We had one infiltrator totally compromise a direct action and another leak which almost ended a protest. Then after me and a housemate were arrested (and released without charges) the local police showed up at our totally hidden illegal sublet. Just walked right up to our hidden door while ignoring the main (landlord's) door with the house number. They came there to have us sign some papers they forgot to have us sign, but obviously surveillance had happened.

So despite very elaborate precautions, it was barely enough to keep a radical activist group functioning. Yeah, I imagine the effort to counter Occupy was pretty substantial. We had like 50 members tops.