You seem to have missed the point.
Disagreements are not remarkable.
People visiting with disagreement as their main goal are the problems.
I usually identify them by their technique: ad hominem and change the subject. Talk about South Africa on a Middle East thread; trot out events of 30 years ago in a discussion of current Mass Murder; Dey the obvious; Make absurd assertions...
Of course, engaging them at all is the mistake. As soon as I suspect, I am happy to leave them talking to themselves.