A few weeks back I came across this passage from Kevin Drum from back in the day. I don't exhume it to pick on Kevin, but I thought it captured something from that time well.
If your opposition to war is based on the idea that Saddam does indeed possess illegal weapons but it's best to leave him alone anyway, well and good. But if it's based on the idea that the administration is lying and none of this stuff exists, you should tread carefully. I think it's pretty likely you will be proven wrong shortly.
Those who opposed the war were constantly being told that they'd better be careful, both in why we opposed the Iraq war and how we expressed that opposition when those views had a complete media blackout... what if Saddam really is dangerous! Then you'll be sorry!!! And, you know what? It's true. If they'd found the nuclear warheads, and the long range missiles, and the massive bioweapons programs, and the deadly drones of mass destruction, or whatever, people like me would've been drummed out of our discourse 4ever. Stupid dirty fucking hippie!
But, hey, if you supported a pointless war which has lead to hundreds of thousands of deaths there was no need to "tread carefully." Bombs away, baby! Bygones.