There are certain arguments, phrases, comparisons and descriptions that will always make me dismiss the speakers opinion. They grate so badly, and are either so fatuous or so instantly disprovable that I simply stop listening. A few might be, for example:
1. Tony Bliar: I didn't much like the chap, but gah, this one got on my tits. Not funny, not clever and makes the speaker sound like he's selling the Socialist Worker.
2. 'David Cameron was Lamont's special adviser on Black Wednesday...': And? He was 23 for God's sake, he wasn't devising monetary policy. It's meaningless and usually uttered in the smug tones of someone convinced they're making a show-stopping point.
3. 'The illegal invasion of Iraq': this is less irritating, I just know that I can switch off from this point on without missing any argument I haven't heard a million times before.
4. 'The rich get richer while the poor get poorer': Translates as 'I do not understand economics; please stab me in the head with a fork'.
5. 'Nazi' 'fascists' or 'apartheid': I obviously have no problem with these when they are used correctly - it's just that they never are these days. In fact, they're usually used in the context of...
6. '...Israel...': I try and switch off in self-defense now. In all honesty, I can hardly summon up the energy to give a stuff about Israel. People who obsess over it are rarely good news.
There are plenty more, but these are the ones that I have consciously noticed making me switch off. They're a verbal shorthand for 'I cannot argue, so I shall fight instead'.