Acceptable agendas when speaking, blogging, posting to bulletin boards (basically whenever you're spouting off your stupid opinion):
~To bring up, reinforce or argue against (with facts or civil statements of mere consent or disagreement), or contribute additional bits of information or insight about a noteworthy topic, whether it be George Lucas's dialogue, butter vs. jelly on English muffins, Mario Lemieux vs. Wayne Gretzky, or the mishandling of the human devastation in hurricane Katrina's aftermath.
*Note* If your sole intention is to say something funny for ALL parties involved, then really, no comments are off-limits.
Unacceptable agendas when speaking, blogging, posting to bulletin boards (basically whenever you're spouting off your stupid opinion):
~Arguing simply to defend or attack a particular ideology, group, or individual - rather than looking objectively at the facts and considering each situation separately. It's fine and logical to allow past experience/observations to help mold your opinion, but keep your political allegiances out of it. (see attacks and especially defenses of Bush Administration).
~Branding those of different viewpoints with terms meant to package them together with other groups that you and your political bedfellows find distasteful. ("You think oil companies need to be restrained? You're a damn liberal PETA-loving tree-hugger communist." "You think it's OK to eat meat? You're a redneck Republican racist fascist dittohead.") This accomplishes nothing.
~Arguing/posting with the real intention of proving how smart you are, disguised as your thoughts on a topic. (see IMDB boards)
~Telling those of different viewpoints that they're just not intelligent enough to understand your statement. (see IMDB boards)
~Speaking with the sole intention of pissing off other parties. *Note* There are cases where this is perfectly acceptable.
And now - I'll link you to Bill Maher's latest Rule about evil.