There are certain topics that are guaranteed to cause "knee jerk" - and usually never-ending- reactions.
Folks have generally made up their minds, and all the discussion in the world won't change their way of thinking. I can usually predict the course of the discussion, and even who will be on what side of the issue.
I try to avoid these, and sometimes I am even successful at doing that!!
Some that occur to me:
vehicular cycling (which should be posted in the VC sub-forum)
Use of words like "old farts," "geezer," etc.
Almost any "political" discussion (P&R instead)
Do you avoid these threads?