@Olivier5,
I respond to unpopular folks sometimes, but not on subjects I've argued with them about before over years, unless I'm particularly fed up; I've limited patience, where others can argue the same thing infinitely, growing healthy bodies twelve ways from doing so (that's a riff on an old commercial).
I'm not a good debater; it was my upbringing not to sass and I learned that arguing was not a sin relatively late as these things go (that bit about arguing was via my schooling and my mother, not so much my father who was around less and had majored in philosophy). I like reading good debate though, part of why I have been here all this time, even now.
I do have some on ignore, rest periods for myself, but I review that and bring people back some part of the time. I've also been known to myself to change my mind from reading other views than my own here, and sometimes tell that straight out when I recognize my change. Usually the change will happen subtlely so I can't pinpoint when that happened.
Given the rancor, this pretty much leaves food and random other matters as pleasant subjects, which people talk about here less. I still love the joke/play/nature threads.
On thumbing, I thumb up, maybe too much. I thumb up for somebody putting in effort to show information/photography/humor, sometimes. I thumb up for things I agree with when well written. Sometimes I thumb up for things I disagree with that are well written. I'm no saint so the latter is used less.
I thumb down as a housecleaning measure for New Post Threads, as opposed to posts. I skim almost all pages of new posts fast, and clear those I will not go back to for curiosity, ever. I leave those where I don't want to hurt the feelings of the posters, new language learners, for example.
On posts within threads, I'll thumb down for awful behavior... not disagreement in itself. I'm also not a saint in this - I have a tendency to be meaner to someone who is, say, repeatedly racist than people I know who are generally reasonable but just pissed off. Usually though, I quickly enough put racists in the ignore village.
I'll thumb down when someone gives execrable advice to an apparent thirteen year old. I guess I'd count that as disagreement, but more a kind of abuse.
On Olivier5, I always listen. His views are often similar to mine and when not, I can see the reasoning. I don't want you to leave.
On whether the world is going to hell without a basket, yes.