I'm like Jane: I will stand up for the underdog if I see them getting dogged out for no particular reason.
There are a few people on this site I do have a soft spot for. They stand out as people who consistently strive to be the best person they can be, even in a tough spot, even when the odds are against them. I have a lot of admiration for those individuals, and will back them up.
Sometimes, I'll send a supportive answer or PM instead of directly confronting the poster who is doing the bashing. I am not going to enlighten the latter; that said, I also know it hurts to have someone say something mean and then to have to walk around with that for the rest of the day. I'd rather provide some gentle encouragement or a 'you were right on'... I figure it's a better use of my energy.