That's true. I think there are two audiences worth thinking about for slogans. The first are people on the demonstration itself, for whom you want a slogan that strengthens morale and, perhaps, makes some kind of political intervention. The second would be people who broadly agree with the demonstration but aren't yet active; I guess what you want to say to them is something like "we're actively involved in politic, you can be too."
I can maybe see the value of the "we are all Hezbollah" slogan in the first case; a strong gesture of solidarity is good motivation, and mentioning Hezbollah in particular is a good challenge to a "they're both as bad as each other" liberalism, even if it is a bit of a "bending the stick" position (trolling as a revolutionary praxis). It's difficult to see it as a good slogan to target the second audience. I wonder how one goes about deciding in each case which audience it's more important to appeal to?
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"Boredom is the threshold to great deeds."
-- Walter Benjamin http://huh.34sp.com/ --------------------------- tim_boetie at fastmail.fm