Well, the basic idea of trash talk isn't to let them expose a reson for you to call them stupid based on logic conclusions, but merely to piss peopel off, so they can't focus on playing their best.
I was playing MW:2 with some friends at one point, and one of them decided it was time for psychological warfare, so whenever a map started, he would hide someplace sortof safe, and just talk (type) trash to teh other team, and he would just go with whatever he could find that might get a response, so when people used their flags colors in their name it was easy.
He would go
"did you hear that "insert country here" is having a major crisis due to underpopulation cause all teh dudes are gay? i mean u can fuck each other all you want, no problem, but at least knock up your chicks for the sake of reproduction" or somehing like that.
Someone always ate teh bait and started whining and ranting, and usually more than one, so teh rest of us could easily pick them off while they were bussy typing.
I don't think they ever realized it was meant as a team-play-weapon and not just some random dude trolling, but then again, if they had ralized that, it would prolly not have worked.