When is it appropriate to take our discontent into the streets in demonstration?Some would assert that it is always time, and I understand that point. Showing (demonstrating) that there is opposition to poor policy is a way to unarguably indicate public opinion. If there are 100,000 Portlanders in the streets asserting something it is impossible for anyone to say, "Polls show their opinion is in the minority."
I think if we keep a few basics in mind it helps us to think about these situations...situationally.
Most importantly, if you aren't recruiting in some fashion, you aren't really moving it forward. Taking it to the streets can recruit or it can turn off everyone except a tiny handful of impotently enraged actors. Taking it to the streets to demonstrate commitment and an invitational stance, as well as willingness to sacrifice but not hurt others, can recruit.
If you are just out there to prove that you are more radical than others, without any strategy or forethought to a recruitment message, you are being unhelpful. I am thinking of one egomaniacal local who always brings a bullhorn and who takes it upon himself to drown out everyone with his harangues. Passersby are absolutely alienated and turn away in disgust. People who come to join our walk often bail early, sick of his stridency and monologic wall of sound. He's not a police agent, but he might as well be.

Attacking people with rage in your heart and a grimace on your face is not invitational to those who happen to see the photo or catch the news report. You quickly drive away potentially active participants when you show hatred. Think of the successful movements and the failures. You'll see my point.
This is why I have an increasingly hard time engaging with the antiwar movement in Portland, my town for the past decade. At our best we were moderating toward a family friendly spirit of our events, and the organizers were clear that they wanted such an atmosphere. In the past few years, however, the organizers have not concerned themselves with their public image nor have they lowered themselves to recruiting from mainstream society. They have spun a radical cocoon around themselves and are shrieking inside it, evermore enraged that others aren't joining them. Somehow, they seem to believe, growing more shrill by the season is what they need to do. It is not working except perhaps cathartically for those who emotionally need such public platforms.

Do they have cause to hate? Of course, and if they could learn the self-discipline that comes with commitment to nonviolence, they would once again be effective. But I attended one of the early organizing meetings for the October 9, 2010 rally and at about 25 minutes into the meeting I asked if there was concern for the image of the event and thus for the behavior of our own people. I was told by the man who had arrogated the leadership position to himself that, "If they're not attacking our people, I don't care what they do." That ended the discussion. No one else participated in it, the group moved on, and I just left. I am done trying to work with groups who don't care about how they come across to average folks, because like it or not, average folks are the only hope in nonviolence, they are the only latent power worth courting and developing. When they are properly engaged, they will act with dispositive authority.
When we organized in late 2002-early 2003 we cared for how we were seen by the mainstream media and we worked with them. We outreached to mainstream churches and unions. We declared our events 'family friendly' and we outreached to elements who wore masks and wanted to wreck things and told them to respect our organizing and not participate unless they could honor our consensed upon spirit. They responded positively and the movement grew, shattering and setting a new Oregon record every time we went out. It was a movement and if every American town had used that model, I wonder if we would have been too powerful to ignore? I wonder if we might have stopped an invasion?
We are apparently done with trying to build a movement in Portland. If anyone becomes interested again, I hope you'll contact me. I remain quite recruitable.