I personally like the method of creating doubt in others and leading others by example. Like I said, I have had friends tell me repeatedly, oh you will get fat if you eat fat, yet now I simply say, well I have lost 30lbs, feel strong, don't look pale, and have plenty of energy, so something must be working. Thus creating doubt in them about their belief that fat = fat.

I have also had a friend of the family ask about what I have been doing and wanted to have the website for Paleodiet.com because weight watchers is just not working for her, and she is feeling hungry all the time.

So I think we make an impact even when we just lead by example.
But I totally understand what you are saying, it is annoying to hear someone bad mouth our WOE, or spread propaganda, while we take a more noble path and say nothing.
So if I hear someone spreading propaganda, I will speak up.
If you really want to see propaganda at work, go to rawveganmom.com .
She is a huge advocate for not eating meat, and will use the same typical scare tactics of animal cruelty to get people to join her cause. I also post on a website that she posts on, and have to constantly counter her propaganda, when she blames all the grain and sugar issues on meat.
But I try to be nice about it and try to remember that she is only trying to do what she feels is right and what she feels is best for others as well.