Gotta agree with Bowser on this one, Tom
Yes, a sign saying "F*** the Troops" is disheartening, but it's Bush who started an unnecessary war and put our troops in a position to be psychologically damaged, physically maimed, or killed. To what end are we extracting such a horrible price? And which is worse, after all, which does more harm--a nasty sign which pisses some people off, or a tragic war in which countless lives are damaged or lost?
If the left has shown some extremism, perhaps it's because it's faced with an administration that is itself showing many disturbing, extemist tendencies.