The tone I most dislike in political blogging is the sneer. Sneering and snideness. The sneering aside that acts as an emotional drive-by rather than direct engagement in the polite and polished civil discourse that provides grounds for civil and civilized disagreement. Irony, when not done in a friendly fashion - irony when really and truly meant - has much the same effect because it means you don't address an argument or a person holding such an argument but instead, in effect, address yourself to an imaginary audience that already agrees with you, sitting in emotional, not rational, judgment upon your subject. It only succeeds as a tone because you have already decided in advance that you are interested merely in conversing with those who already agree with you, and conveys the message to anyone else that you are not interested in discussion, but only in a priori agreement. It is an emotional tone in lieu of reasoned discussion, and serves as gatekeeper (I'm only interested in those who already agree with me) through affect, rather than an invitation to reason together. I try not to indulge that here; not sure I always succeed.