I think this is far too broad and all encompassing a stance. Were the Plastic People of the Universe dissidents in the Czech Republic? All they wanted to do was play music, they were challenging ideas and taboos and censorship (and weren't a particularly great band I think on a musical level) but still by far they were the major factor in the Czech's Velvet Revolution (and, as a Velvet Underground cover band the reason it was CALLED a Velvet Revolution). And yet I don't believe they BECAME dissidents when people TOOK their expression and demanded the right from the whole government for reforms, nor do I think "real" dissidents took their ideas and BECAME dissidents as a result.
I think a dissident is someone that challenges an accepted institutional power structure. If anything I think the most effective tools are often something we would consider frivolous today because we HAVE freedoms. Reason magazine (yes, I know, libertarian magazine, get over it and listen) did an interesting story before the "Arab Spring"
about Egypt and Metal bands. It would be irresponsible to say that THEY brought down Mubarak and his government but I think was an indicator, a canary in the coal mine if you will of what was to come. It was another point for people to coalesce around and believe the government was being overly restrictive.
I don't think it takes mere opposition (saying "I do not believe the PATRIOT Act is good policy" for example) to make someone a dissident. I think working to subvert an institution KNOWING it is in power and your action flies in the face of the institution you're opposing making you vulnerable to arrest or other sanction. So for example I think the "Don't touch my junk" guy was a dissident against the TSA. I think the Cao Ni Ma creators were dissidents because it was a direct effort to subvert the political will of China and would probably leave the creator vulnerable to arrest. I think Rosa Parks was a dissident because she did not follow the law. Aung San Suu Kyi, dissident. Aleksandr Solzhenitsyn - dissident. Medgar Evers - dissident. Dissidents actively challenge the system, sometimes by their very presence and a tiny action, but it's an act that spits in the face of the institutional regime they oppose.