I've never put anyone on an ignore list, for several reasons. It doesn't bother me to have someone disagree with me, and a debate over a subject is just that. A subject. People are not one-dimensional. We may disagree here, and completely agree there.
I also believe that if I'm going to put it out there, I should be prepared to get something back, positive or negative. And, I appreciate that someone is different than me. Sometimes I learn something new, and sometimes I adjust my stance. I have no problem admitting when I am wrong. If I ignore someone I might miss a pertinent point.
I will ignore a post that has nothing constructive to it. For instance, "I don't like your point of view so you are a &%^$$" as opposed to "I don't like your point of view because of a, b, and c.