I've now had it pointed out to me by several people that there's no point asking people to be polite when they're discussing things on the internet - because the tone they take doesn't actually affect how people's views are taken.
The most recent time I was linked to this post, which is well written, amusing, and completely failed to make its point to me. Their point was that speaking politely doesn't work. That people have tried speaking politely, and got nowhere.
My point is that they offer absolutely no evidence that shouting _does_ work. And in my experience, shouting pushes people away more than anything else.
I don't have a racism example, because I've not been accused of racism. However, I have been accused of sexism. And I'm fairly sure that I have been sexist - but the way that I was approached managed to both shut off any chance that I was going to listen to what the person was saying, but also caused a few other people to feel disgusted at what they were saying. It caused people to speak negatively of "feminists" - something I had to then try and correct (what with being one myself).
If someone has evidence that shouting at bigots actually achieves any good then I would be very happy to hear it. Provided that it's presented to me in a reasonable, non-offensive manner. I may even change my mind :->