I also think that the right wing argument that 'the left does it too' is a hugely offensive red herring.
It justifies bad behaviour and evades responsibility by asserting moral equivalence.
In short 'my bad conduct is acceptable and moral because my enemy engages in similar conduct.'
In shorter 'my bad conduct is justified by what I *believe* my enemy is doing.'
Let me explain something: If your moral floor is defined by what you imagine to be the worst quality of your enemy.... you have no moral floor. You have no morals.
Frankly, any response to Right Wing eliminationism that starts off by looking at left wing misconduct is simple and utter bullshit.
The language of the left may be a subject for examination and discussion in turn.
But in its current use, its merely an attempt to avoid the real issue.
I think the people who use "the other side does it too" as a conclusive argument don't understand what ethics is for. To my mind, ethics is a way of improving the odds of getting good long term outcomes. It's a challenging subject because it's all so probabilistic that it's hard to be sure whether you're getting it right. However, ethics is not there to be a way of proving you meet a minimum standard of okness.
On the mental hygiene side, it's really tempting to give all your attention to the worst of the other side. I admit I'm not good at looking for their best, but I at least try to find the main tendency rather than the worst.
Notes: The quote is from comments to Orcinus. I hate Haloscan.
Regardless of what my spellchecker thinks, I want "longterm" to be one word. However, "shortterm" looks too weird, so I'm conforming to the majority.
Link thanks to dglenn.