I give none to those I deem harmful.
An example came up today where someone argued that the Civil War was not caused by Southern insistence on preserving Slavery. To me, that is a crackpot idea. If you want to know why I think so, you can search Civil War/slavery/Armando in comments and archive and I say so. I really think it does not bear repeating. I really believe no serious student of American History can think that. That is my sincere belief.
I also believe that denials of the Holocaust are crackpot. I won't discuss that issue seriously either. I also believe that those who would have creationism taught in science class in schools are crackpot. I won't discuss that issue seriously either.
Now I'm sure there are harmless crackpot theories that I won't denounce. Can't think of any off the top of my head right now. But my differentiation with the 3 I describe above is I find those 3 harmful - the Lost Cause myth has stunted race relations in this country for 150 years. The Holocaust denials have fueled neo-Nazism and antisemitism. The Creationist movement is nothing but an attack on science. I think they are harmful and to treat them with seriousness does further harm. I have no objection to debunkings in the academy, but here at dkos, I think it doesn't help. Encourages trolling. For those who really want to know more on the subjects - remember, google is your friend.