@stefko hi Stefko. I answered your survey. But some of my answers may not be as informative as you'd like: I don't use Home or Local feeds, only lists and #, so I'm not so aware of noise on my own instance. I noted this as a comment at the end.
I'm more aware of trolls on other instances, and I block those accounts - though, often by the time I spot them, they've been blocked (good work, moderators).
Best wishes for your studies.
Deb