Late to the ball with this, I know. But I absloutely agree with Caster. If you disagree with a post strongly enough to comment, do it privately. Being obnoxious and actively damaging, or potentially damaging someone else's sale is just not right or even anything other that downright rude.
I've disagreed with some items, sure. But not enough to make an ass of myself publically. I try to just roll with it and chalk it up to poor raising or just stupidity.
I recently had a trade offer commented on by a newbie, telling the OP to go somewhere else. It wasn't his business to interfere with. So he should have stayed our, or done it privately, not publically. I held my comments, knowing this was a noob.
Maybe a quiz on how to conduct one's self should be mandatory before being allowed to post. Seems lately that a lot of newcomers could benefit from it.
Rant over.