Protests are effective if there’s a credible threat to those with the power to change whatever is being protected about. If the protesters do not pose a threat of any kind (and I don’t mean just one of physical violence, since that’s often one of the least effective potential threats, although it can have value at times) then nothing will change.

But protesting where you cause an inconvenience to those who neither support nor oppose the protesters can often be a bad move. On occasion it can serve to bring people’s attention to the issue and convince them, but in my experience, if the first experience someone has with an issue, the first awareness they have of it is some protest that caused them problems, that person is likely to be disinclined to become a supporter of the cause, and indeed is often likely to be pushed towards opposing and cracking down on the protest.

This of course can backfire, since if the protesters pose an electoral threat, for instance, and the protests cause a bunch of people to be angry at them and just want the crap to end, those in power are given the message that hey…there’s support for just getting rid of the protesters.