Gary Rosenblatt, of the New York Jewish Week, makes some excellent points here about the so-called watch groups which totally miss the point and make any dialogue impossible.

Moreover, this new effort is representative of what Martin Raffel, the Jewish Council for Public Affairs senior vice president, calls a growing trend — the downside of the “democratization of advocacy.”
As head of a communal effort to counter delegitimization efforts, he sees more and more individuals and small groups able to mobilize sentiment easily and quickly on the Internet today, often with disturbing effects.
“There is very little filtering, verifying facts, putting issues in context, or looking at strategic objectives,” he said. “Anyone with a PC is an organization now, answerable only to themselves. And they are injecting themselves into the bloodstream of Jewish discourse, reaching thousands of people, and making our work more difficult.”
The new advocates tend to be “rebellious toward the establishment and feel they have the corner on the truth,” says Raffel, “and we have to grapple” with the fallout.
In addition, efforts like JCCWatch divert attention away from the real issues we should be confronting.

Sometimes, these one-man-and-a-dog "watchers" wilfully misunderstand what is written and seek to impose their own narrow agenda. What they appear not to understand is that by being shouty and aggressive, they are handing a victory to those who want to see Israel's demise as the homeland of the Jewish nation.
As Rosenblatt says:

let’s start by agreeing that targeting our own, aggressively and irresponsibly, hurts our cause and our community.