Humayun and PragueTory have inspired me (is this thus a meme now?). The big question with propaganda is whether it is propaganda in itself. We can call something a good argument, if we agree and support the communicator and believe their motives are honourable; or say 'pah, that's just propaganda' if we disagree and dislike communicator and their motives; what does that tell us? Nothing?
The problem is that we live in a society of spin. If I am late I blame traffic, buses etc; seldom would I say I couldn't be bothered to get my sorry XXXX into gear and get somewhere on time when that is really the truth. This means that 'spin' tends to be a universal code of language which we all accept and choose to ignore or highlight. We decide what is acceptable 'SMART' spin, a white lie maybe, in what context, maybe to make someone feel better about themselves; and what is bad, unacceptable and misleading.
The problem for politics is that it doesn't matter if the motives are really honourable, or that a political actor/activist, is trying to present a persuasive case; often it is simply consigned to the dustbin as propaganda - 'Well they would say that wouldn't they' or 'They just want our money / votes'. Looking outside of the UK to the US, Obama is building a populist campaign around big tent politics. His purpose maybe to reunite America, the bottom line is he wants to raise money to support his campaign for he Democratic nomination. So do we shout propaganda, is it misleading and manipulative, or do we shout 'good campaigning' as it is persuasive and appealing. It is probably a question of perspectives!